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TABLE OF CONTENTS
ABOUT THE AUTHORS I
ACKNOWLEDGEMENTS II
PREFACE III
CHEMISTRY, MATTER, AND MEASUREMENT 1
ELEMENTS, ATOMS, AND THE PERIODIC TABLE 10
IONIC BONDING AND SIMPLE IONIC COMPOUNDS 20
COVALENT BONDING AND SIMPLE MOLECULAR COMPOUNDS 30
INTRODUCTION TO CHEMICAL REACTIONS 40
QUANTITIES IN CHEMICAL REACTIONS 50
ENERGY AND CHEMICAL PROCESSES 60
SOLIDS, LIQUIDS, AND GASES 70
SOLUTIONS 80
ACIDS AND BASES 90
ARRHENIUS DEFINITION OF ACIDS AND BASES 100
BRØNSTED-LOWRY DEFINITION OF ACIDS AND BASES 110
WATER: BOTH AN ACID AND A BASE 120
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THE STRENGTHS OF ACIDS AND BASES 130
BUFFERS 130
END-OF-CHAPTER MATERIAL 140
NUCLEAR CHEMISTRY 150
ORGANIC CHEMISTRY: ALKANES AND HALOGENATEDHYDROCARBONS 160
UNSATURATED AND AROMATIC HYDROCARBONS 170
ORGANIC COMPOUNDS OF OXYGEN 180
ORGANIC ACIDS AND BASES AND SOME OF THEIR DERIVATIVES 190
CARBOHYDRATES 120
LIPIDS 130
AMINO ACIDS, PROTEINS, AND ENZYMES 140
NUCLEIC ACIDS 150
ENERGY METABOLISM 160
APPENDIX: PERIODIC TABLE OF THE ELEMENTS 170
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CHAPTER 1: CHEMISTRY, MATTER, AND MEASUREMENT ANDELECTRON STRUCTURE OF ATOMS
In April 2003, the US Pharmacopeia, a national organization that establishes quality standards for medications, reported a case in which a physician ordered ―morphine [a powerful painkiller]
2–3 mg IV [intravenously] every 2–3 hours for pain.‖ A nurse misread the dose as ―23 mg‖ and thus administered approximately 10 times the proper amount to an 8-year-old boy with a broken
leg. The boy stopped breathing but was successfully resuscitated and left the hospital three days later.Quantities and measurements are as important in our everyday lives as they are in
medicine. The posted speed limits on roads and highways, such as 55 miles per hour (mph), are quantities we might encounter all the time. Both parts of a quantity, the amount (55) and the unit
(mph), must be properly communicated to prevent potential problems. In chemistry, as in any technical endeavor, the proper expression of quantities is a necessary fundamental skill. As we
begin our journey into chemistry, we will learn this skill so that errors—from homework mistakes to traffic tickets to more serious consequences—can be avoided.The study of chemistry will
open your eyes to a fascinating world. Chemical processes are continuously at work all around us. They happen as you cook and eat food, strike a match, shampoo your hair, and even read this
page. Chemistry is called the central science because knowledge of chemical principles is essential for other sciences. You might be surprised at the extent to which chemistry pervades your life.
What Is Chemistry: Learning Objectives
Define chemistry in relation to other sciences.Identify the general steps in the scientific method.Chemistry is the study of matter—what it consists of, what its properties are, and how it changes.
Being able to describe the ingredients in a cake and how they change when the cake is baked is called chemistry. Matter is anything that has mass and takes up space—that is, anything that is
physically real. Some things are easily identified as matter—this book, for example. Others are not so obvious. Because we move so easily through air, we sometimes forget that it, too, is
matter.Chemistry is one branch of science. Science is the process by which we learn about the natural universe by observing, testing, and then generating models that explain our observations.
Because the physical universe is so vast, there are many different branches of science (). Thus, chemistry is the study of matter, biology is the study of living things, and geology is the study of
rocks and the earth. Mathematics is the language of science, and we will use it to communicate some of the ideas of chemistry.Although we divide science into different fields; there is much
overlap among them. For example, some biologists and chemists work in both fields so much that their work is called biochemistry. Similarly, geology and chemistry overlap in the field called
geochemistry. Shows how many of the individual fields of science are related.
Figure 1.1 the Relationships between Some of the Major Branches of Science
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Chemistry lies more or less in the middle, which emphasizes its importance to many branches of science.Note: There are many other fields of science, in addition to the ones (biology, medicine,
etc.) listed here.Looking Closer: AlchemyAs our understanding of the universe has changed over time, so has the practice of science. Chemistry in its modern form, based on principles that we
consider valid today, was developed in the 1600s and 1700s. Before that, the study of matter was known as alchemy and was practiced mainly in China, Arabia, Egypt, and Europe.Alchemy was
a somewhat mystical and secretive approach to learning how to manipulate matter. Practitioners, called alchemists, thought that all matter was composed of different proportions of the four
basic elements fire, water, earth, and air and believed that if you changed the relative proportions of these elements in a substance, you could change the substance. The long-standing attempts
to ―transmute‖ common metals into gold represented one goal of alchemy. Alchemy’s other major goal was to synthesize the philosopher’s stone, a material that could impart long life—even
immortality. Alchemists used symbols to represent substances, some of which are shown in the accompanying figure. This was not done to better communicate ideas, as chemists do today, but to
maintain the secrecy of alchemical knowledge, keeping others from sharing in it.
Alchemists used symbols like these to represent substances.In spite of this secrecy, in its time alchemy was respected as a serious, scholarly endeavor. Isaac Newton, the great mathematician and
physicist, was also an alchemist.Example 1.Which fields of study are branches of science? Explain.sculpture, astronomy; SolutionSculpture is not considered a science because it is not a study of
some aspect of the natural universe.Astronomy is the study of stars and planets, which are part of the natural universe. Astronomy is therefore a field of science.Skill-Building Exercise; which
fields of study are branches of science? Politics; physiology (the study of the function of an animal’s or a plant’s body), geophysics, agriculture.How do scientists work? Generally, they follow a
process called the scientific method. The scientific method is an organized procedure for learning answers to questions. To find the answer to a question (for example, ―Why do birds fly toward
Earth’s equator during the cold months?‖), a scientist goes through the following steps, which are also illustrated in:Figure 1.2 the General Steps of the Scientific Method
The steps may not be as clear-cut in real life as described here, but most scientific work follows this general outline.
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Propose a hypothesis. A scientist generates a testable idea, or hypothesis, to try to answer a question or explain how the natural universe works. Some people use the word theory in place of
hypothesis, but the word hypothesis is the proper word in science. For scientific applications, the word theory is a general statement that describes a large set of observations and data. A theory
represents the highest level of scientific understanding.Test the hypothesis. A scientist evaluates the hypothesis by devising and carrying out experiments to test it. If the hypothesis passes the
test, it may be a proper answer to the question. If the hypothesis does not pass the test, it may not be a good answer.Refine the hypothesis if necessary. Depending on the results of experiments, a
scientist may want to modify the hypothesis and then test it again. Sometimes the results show the original hypothesis to be completely wrong, in which case a scientist will have to devise a new
hypothesis.Not all scientific investigations are simple enough to be separated into these three discrete steps. But these steps represent the general method by which scientists learn about our
natural universe.Concept Review Exercises: Define science and chemistry.Name the steps of the scientific method.Answers;Science is a process by which we learn about the natural universe by
observing, testing, and then generating models that explain our observations. Chemistry is the study of matter.propose a hypothesis, test the hypothesis, and refine the hypothesis if necessa.Key
Takeaways.Chemistry is the study of matter and how it behaves.The scientific method is the general process by which we learn about the natural universe.Exercises:Based on what you know,
which fields are branches of science?;meteorology (the study of weather);astrophysics (the physics of planets and stars);economics (the study of money and monetary systems);astrology (the
prediction of human events based on planetary and star positions);political science (the study of politics);Based on what you know, which fields are a branches of science?;history (the study of
past events);ornithology (the study of birds);paleontology (the study of fossils);zoology (the study of animals);phrenology (using the shape of the head to determine personal
characteristics).Which of the following are examples of matter?a baby an idea,the Empire State Building an emotion the air.Alpha Centauri, the closest known star (excluding the sun) to our
solar system.Which of the following are examples of matter?;your textbook,brain cells,love,a can of soda,breakfast cereal,Suggest a name for the science that studies the physics of rocks and the
earth.Suggest a name for the study of the physics of living organisms.Engineering is the practical application of scientific principles and discoveries to develop things that make our lives easier.
Is medicine science or engineering? Justify your answer.Based on the definition of engineering in Exercise 7, would building a bridge over a river or road be considered science or engineering?
Justify your answer.When someone says, ―I have a theory that excess salt causes high blood pressure,‖ does that person really have a theory? If it is not a theory, what is it? When a person says,
―My hypothesis is that excess calcium in the diet causes kidney stones,‖ what does the person need to do to determine if the hypothesis is correct.Some people argue that many scientists accept
many scientific principles on faith. Using what you know about the scientific method, how might you argue against that assertion?.Most students take multiple English classes in school. Does the
study of English use the scientific method?Answers;science;science;not science;not science;not science;matter;not matter;matter;not matter;matter;matter and geophysics.Medicine is probably
closer to a field of engineering than a field of science, but this may be arguable. Ask your doctor.In scientific terms, this person has a hypothesis.Science is based on reproducible facts, not blind
belief.
THE CLASSIFICATION OF MATTER
LEARNING OBJECTIVES;Use physical and chemical properties, including phase, to describe matter.Identify a sample of matter as an element, a compound, or a mixture.Part of
understanding matter is being able to describe it. One way chemists describe matter is to assign different kinds of properties to different categories.
Physical and Chemical Properties:The properties that chemists use to describe matter fall into two general categories. Physical properties are characteristics that describe matter. They include
characteristics such as size, shape, color, and mass. Chemical properties are characteristics that describe how matter changes its chemical structure or composition. An example of a chemical
property is flammability—a material’s ability to burn—because burning (also known as combustion) changes the chemical composition of a material.Elements and Compounds:Any sample of
matter that has the same physical and chemical properties throughout the sample is called a substance. There are two types of substances. A substance that cannot be broken down into
chemically simpler components is an element. Aluminum, which is used in soda cans, is an element. A substance that can be broken down into chemically simpler components (because it has
more than one element) is a compound (). Water is a compound composed of the elements hydrogen and oxygen. Today, there are about 118 elements in the known universe. In contrast,
scientists have identified tens of millions of different compounds to date.
Note:Sometimes the word pure is added to substance, but this is not absolutely necessary. By definition, any single substance is pure.The smallest part of an element that maintains the identity
of that element is called an atom. Atoms are extremely tiny; to make a line 1 inch long, you would need 217 million iron atoms. The smallest part of a compound that maintains the identity of
that compound is called a molecule. Molecules are composed of atoms that are attached together and behave as a unit. Scientists usually work with millions and millions of atoms and molecules
at a time. When a scientist is working with large numbers of atoms or molecules at a time, the scientist is studying the macroscopic view of the universe. However, scientists can also describe
chemical events on the level of individual atoms or molecules, which is referred to as the microscopic viewpoint. We will see examples of both macroscopic and microscopic viewpoints
throughout this book ().Figure 1.3 How Many Particles Are Needed for a Period in a Sentence?
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Although we do not notice it from a macroscopic perspective, matter is composed of microscopic particles so tiny that billions of them are
needed to make a speck we can see with the naked eye. The ×25 and ×400,000,000 indicate the number of times the image is magnified.Mixtures:A material composed of two or more substances
is a mixture. In a mixture, the individual substances maintain their chemical identities. Many mixtures are obvious combinations of two or more substances, such as a mixture of sand and
water. Such mixtures are called heterogeneous mixtures. In some mixtures, the components are so intimately combined that they act like a single substance (even though they are not). Mixtures
with a consistent composition throughout are called homogeneous mixtures (or solutions). Sugar dissolved in water is an example of a solution. A metal alloy, such as steel, is an example of a
solid solution. Air, a mixture of mainly nitrogen and oxygen, is a gaseous solution.Example 2; How would a chemist categorize each example of matter? Saltwater, soil, water, oxygen.Solution:
Saltwater acts as if it were a single substance even though it contains two substances—salt and water. Saltwater is a homogeneous mixture, or a solution.Soil is composed of small pieces of a
variety of materials, so it is a heterogeneous mixture.Water is a substance; more specifically, because water is composed of hydrogen and oxygen, it is a compound.Oxygen, a substance, is an
element.Skill-Building Exercise;How would a chemist categorize each example of matter?;coffee,hydrogen,an egg.
Phases:Another way to classify matter is to describe it as a solid, a liquid, or a gas, which was done in the examples of solutions. These three descriptions, each implying that the matter has
certain physical properties, represent the three phases of matter. A solid has a definite shape and a definite volume. Liquids ordinarily have a definite volume but not a definite shape; they take
the shape of their containers. Gases have neither a definite shape nor a definite volume, and they expand to fill their containers. We encounter matter in each phase every day; in fact, we
regularly encounter water in all three phases: ice (solid), water (liquid), and steam (gas).We know from our experience with water that substances can change from one phase to another if the
conditions are right. Typically, varying the temperature of a substance (and, less commonly, the pressure exerted on it) can cause a phase change, a physical process in which a substance goes
from one phase to another (). Phase changes have particular names depending on what phases are involved, as summarized in .Table 1.1 Phase Changes
Change Name
solid to liquid melting, fusion
solid to gas sublimation
liquid to gas boiling, evaporation
liquid to solid solidification, freezing
gas to liquid condensation
gas to solid deposition
Figure 1.4 Boiling Water
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When liquid water boils to make gaseous water, it undergoes a phase change.illustrates the relationships between the different ways matter can
be classified.
Figure 1.5 the Classification of Matter
Matter can be classified in a variety of ways, depending on its properties.Concept Review Exercises:Explain the differences between the physical properties of matter and the chemical
properties of matter.What is the difference between a heterogeneous mixture and a homogeneous mixture? Give an example of each.Give at least two examples of a phase change and state the
phases involved in each.Answers:Physical properties describe the existence of matter, and chemical properties describe how substances change into other substances.A heterogeneous mixture is
obviously a mixture, such as dirt; a homogeneous mixture behaves like a single substance, such as saltwater.solid to liquid (melting) and liquid to gas (boiling) (answers will vary);Key
Takeaways.Matter can be described with both physical properties and chemical properties.Matter can be identified as an element, a compound, or a mixture.Exercises:Does each statement
refer to a chemical property or a physical property?.Balsa is a very light wood.If held in a flame, magnesium metal burns in air.Mercury has a density of 13.6 g/mL.Human blood is red.Does
each statement refer to a chemical property or a physical property?The elements sodium and chlorine can combine to make table salt.The metal tungsten does not melt until its temperature
exceeds 3,000°C.The ingestion of ethyl alcohol can lead to disorientation and confusion.The boiling point of isopropyl alcohol, which is used to sterilize cuts and scrapes, is lower than the boiling
point of water.Define element. How does it differ from a compound?.Define compound. How does it differ from an element?;Give two examples of a heterogeneous mixture.Give two examples of
a homogeneous mixture.Identify each substance as an element, a compound, a heterogeneous mixture, or a solution.xenon, a substance that cannot be broken down into chemically simpler
components.blood, a substance composed of several types of cells suspended in a salty solution called plasma.water, a substance composed of hydrogen and oxygen.Identify each substance as an
element, a compound, a heterogeneous mixture, or a solution.sugar, a substance composed of carbon, hydrogen, and oxygen.hydrogen, the simplest chemical substance.dirt, a combination of
rocks and decaying plant matter.Identify each substance as an element, a compound, a heterogeneous mixture, or a solution.air, primarily a mixture of nitrogen and oxygen.ringer’s lactate, a
standard fluid used in medicine that contains salt, potassium, and lactate compounds all dissolved in sterile water.tartaric acid, a substance composed of carbon, hydrogen, and oxygen.Identify
each material as an element, a compound, a heterogeneous mixture, or a solution.equal portions of salt and sand placed in a beaker and shaken up.a combination of beeswax dissolved in liquid
hexane.hydrogen peroxide, a substance composed of hydrogen and oxygen.What word describes each phase change?solid to liquid,liquid to gas,solid to gas.What word describes each phase
change?;liquid to solid,gas to liquid,gas to solid.Answers;physical property,chemical property,physical property,physical property.An element is a substance that cannot be broken down into
chemically simpler components. Compounds can be broken down into simpler substances.a salt and pepper mix and a bowl of cereal (answers will vary);element,heterogeneous
mixture,compound;solution;solution,compound,melting or fusion,boiling or evaporation and sublimation1.3 Measurements:Learning Objective
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Express quantities properly, using a number and a unit.A coffee maker’s instructions tell you to fill the coffeepot with 4 cups of water and use 3 scoops of coffee. When you follow these
instructions, you are measuring. When you visit a doctor’s office, a nurse checks your temperature, height, weight, and perhaps blood pressure (). The nurse is also measuring.Figure 1.6
Measuring Blood Pressure
A nurse or a doctor measuring a patient’s blood pressure is taking a measurement.Chemists measure the properties of matter and express these measurements as
quantities. A quantity is an amount of something and consists of a number and a unit. The number tells us how many (or how much), and the unit tells us what the scale of measurement is. For
example, when a distance is reported as ―5 kilometers,‖ we know that the quantity has been expressed in units of kilometers and that the number of kilometers is 5. If you ask a friend how far
he or she walks from home to school and the friend answers ―12 without specifying a unit, you do not know whether your friend walks—for example, 12 miles, 12 kilometers, 12 furlongs, or 12
yards. Both a number and a unit must be included to express a quantity properly.To understand chemistry, we need a clear understanding of the units chemists work with and the rules they follow
for expressing numbers. The next two sections examine the rules for expressing numbers.Example 3;Identify the number and the unit in each quantity.;one dozen eggs,2.54 centimeters,a box of
pencils,88 meters per second.Solution;The number is one, and the unit is dozen eggs.The number is 2.54, and the unit is centimeter.The number 1 is implied because the quantity is only a box.
The unit is box of pencils.
The number is 88, and the unit is meters per second. Note that in this case the unit is actually a combination of two units: meters and seconds.Skill-Building Exercise;Identify the number and
the unit in each quantity.99 bottles of soda,60 miles per hour,32 fluid ounces,98.6 degrees Fahrenheit;Concept Review Exercise,What are the two necessary parts of a quantity?Answer The two
necessary parts are the number and the unit.To Your Health: Dosages.As we saw in the chapter-opening essay, a medicine can be more harmful than helpful if it is not taken in the proper
dosage. A dosage (or dose) is the specific amount of a medicine that is known to be therapeutic for an ailment in a patient of a certain size. Dosages of the active ingredient in medications are
usually described by units of mass, typically grams or milligrams, and generally are equated with a number of capsules or teaspoonfuls to be swallowed or injected. (For more information about
mass, see .) The amount of the active ingredient in a medicine is carefully controlled so that the proper number of pills or spoonfuls contains the proper dose.Most drugs must be taken in just
the right amount. If too little is taken, the desired effects will not occur (or will not occur fast enough for comfort); if too much is taken, there may be potential side effects that are worse than
the original ailment. Some drugs are available in multiple dosages. For example, tablets of the medication levothyroxine sodium, a synthetic thyroid hormone for those suffering from decreased
thyroid gland function, are available in 11 different doses, ranging from 25 micrograms (µg) to 300 µg. It is a doctor’s responsibility to prescribe the correct dosage for a patient, and it is a
pharmacist’s responsibility to provide the patient with the correct medicine at the dosage prescribed. Thus, proper quantities—which are expressed using numbers and their associated units—
are crucial for keeping us healthy.
Key Takeaway
Identify a quantity properly with a number and a unit.
Exercises
Why are both parts of a quantity important when describing it?
Why are measurements an important part of any branch of science, such as chemistry?
You ask a classmate how much homework your chemistry professor assigned. Your classmate answers, ―twenty.‖ Is that a proper answer? Why or why not?
Identify the number and the unit in each quantity.
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five grandchildren
16 candles
four score and seven years
40 days and 40 nights
12.01 grams
9.8 meters per second squared
55 miles per hour
98.6 degrees Fahrenheit
Answers
The number states how much, and the unit states of what. Without the number and the unit, a quantity cannot be properly communicated.
No, it is not a proper answer; you do not know whether the professor meant homework problem number 20 or 20 homework problem
LEARNING OBJECTIVES:
Electromagnetic Radiation is energy and light. We will learn how to use it to explore atomic structure.Bohr’s Theory of atomic structure is the beginning of quantum theory and describes
electrons as residing in very particular "quantized" energy levels within the atom.Shells, Sub-shells and Orbital’s are the backbone of the organizational structure of electrons in the
atomElectron Configurations use shells, sub-shells and orbital to describe the relative electronic organization within the atom.Periodicity;Of electron configurations relate to periodicity of
physical and chemical properties.Of valence shell configurations relate directly to relative reactivity.We know that an element is defined by the number of protons it contains. Now we will learn
how electrons and their particular arrangement within an atom can affect how that atom reacts, chemically and physically.
ELECTROMAGNETIC RADIATION: What is it, why is it important to our discussion about atoms and the arrangement of their electrons? .Electromagnetic radiation is energy – we describe
it as a wave – visible light is only a small portion of the electromagnetic spectrum. Each type of energy (x-rays, gamma-rays, microwaves, radio waves) as well as each type of light (red, blue,
green) has different wave characteristics. The characteristics which distinguish different types of light are the electromagnetic radiations;wavelength ,frequency andEnergy.
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Wavelength; the distance between two peaks (or two troughs) of the wave.Frequency; the number of wavelengths passing a given point in one second.The longer the wavelength, the more time it
takes for a full wave to pass a given point (or the fewer waves pass the point in a given time). Since frequency is wavelengths per second, as the wavelength becomes longer the frequency
decreases, and vice versa.Energy ; is directly proportional to the frequency-- if the frequency increases, so does the energy of the radiation and vice [12] versa.
When atoms are excited by energy (such as heat) – they emit energy in the form of light (sometimes colored light) and different atoms emit different energies.What causes the emission of light?
Electron transitions from higher to lower energy levels, which we will learn about when we discuss the structure of the atom. Why do different atoms emit different light? .Each atom is unique
and contains its own unique electron structure in which the energies of the levels mentioned above differ.How does the emission of light relate to electron structure?.Since each atom has a
unique electron structure with differing levels of energy, the energy of the transitions between those levels will also be unique.These energy spectra are how scientists explore the universe today-
-to learn the content of stars, whether the universe is expanding, etc.
Bohr’s Theory: When white light is passed through a prism, it is separated into its components of the spectrum, or the "rainbow" of colors. What, then, is white light made of? This "rainbow"
is called a continuous spectrum, as shown below (look familiar?):
When atoms are excited they emit light--but not as a continuous spectrum. The light is emitted as a specific pattern of visible, colored lines which is particular to each element. Hence these line
spectra can be used to identify individual elements. The hydrogen line spectrum is shown below:
Why do elements not emit continuous spectra and why does each element emit a particular set of lines which make up its line spectrum?.The answer lies in Bohr's Theory of the Atom and its
structure. Bohr found that:electrons move in particular 'orbits' within the atom--meaning electrons have particular places or levels within the atom,electrons have certain allowed energy
values,the closer the electron is to the nucleus, the lower the energy (the more negative the value or the value is toward the bottom of the number scale . . . -4, -3, -2, -1, 0, 1, 2, 3, 4, . . . .),
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when electrons are excited, they gain (or absorb) energy and move to a higher level (farther away from the nucleus),when electrons give off light, they emit energy and move to a lower level
(closer to the nucleus),Following are two graphics which show this effect:
When electrons are excited they absorb energy and move to a higher energy level (gold arrow). When they emit light, they move to a lower energy level. Violet light (violet arrow) is produced
when electrons move from level 6 to level 2. Blue light (blue arrow) is produced when electrons move from level 5 to level 2. Green light (green arrow) is produced when electrons move from
level 4 to level 2. Red light (red arrow) is produced when electrons move from level 3 to level 2. This series of lines which is the visible hydrogen line spectrum is called the Balmer series. The
energies of these emissions just happen to be in the visible range so we can see the colors. There are many other transitions which occur, but since they are not in the visible range we cannot see
them. Some have wavelengths less than 400 nm and some have wavelengths greater than 750 nm (remember, the visible range is very limited, only 400-750 nm).
SHELLS, SUBSHELLS, ORBITALS:Visualize the atom as an onion with different levels of structure and sub-structure, all of which make up electron energy levels – each major energy level is
designated by a number (called the quantum number): Major Shell :The major shell is the major layer of the onion--the large, thick peels which make you cry when you chop them. The major
shells are designated by numbers which have integral values of 1, 2, 3, etc.These numbers are designated as the major shell quantum numbers, n.n = 1 designates the first major shell, the one
closest to the nucleus and the one with the lowest (most negative) energy;
n = 2 designates the second major shell, a little further from the nucleus;n = 3 designates the third major shell, etc. The major shell is the primary influence on the energy of the electron.The
electron "assumes" the energy of the major shell in which it resides.The closer the (negative) electron is to the (positive) nucleus, the stronger the attraction will be, and the harder the electron is
to remove. So an electron in shell n=1 will be very hard to remove while an electron in shell n=4 would be much easier to remove.Major shells contain sub shells which are a substructure within
the major shell. The number of the sub shells is the same as the quantum number of the major shell, For example, major shell n = 1 has one sub shell (specifically, an 's' sub shell); n = 2 has two
sub shells (an 's' and a 'p' sub shell), n = 3 has three sub shells (s, p, and d sub shells), and n = 4 has four sub shells (s, p, d and f).Sub shell :The sub shells are a substructure within the major
shells--imagine each onion skin or peel containing another set of peels within each major peel.The subshells are designated by letters s, p, d, f (these letters are terms which originated from the
field of spectroscopy). s, p, d, and f are different types of subshells which have different properties which we will learn about soon. These subshells contain a further substructure, which are sets
of orbitals which have the same energy.OrbitalsEach subshell is further structured into orbitals.
s subshells have one orbital,p subshells have three, equal energy orbitals,d subshells have five, equal energy orbitals and f subshells have seven, equal energy orbitals;each orbital can
accommodate a maximum of two electrons, and;each orbital takes on the characteristics of its subshell and major shell.s subshell orbitals (there is only one per major shell) are spherical,p
subshell orbitals (there are three of them per major shell) are dumbell shaped and directed along the x, y and z axis,d subshell orbitals (there are five of them per major shell) have a different
shape [I only want you to recognize s and p shapes].Below is shown the relative energy levels and structure of the hydrogen atom. Remember, n = 1 is the major shell closest to the nucleus and it
has only one subshell which, in turn, contains only one orbital, which can contain two electrons. What is the maximum number of electrons that can reside in the first major shell? In the
diagram, the major shells are designated by the black lines coming from the energy arrow. The different types of subshells are indicated by the differently colored boxes. The orbitals themselves
are the individual boxes. Remember, each box (orbital) can contain only a maximum of two electrons. Consequently, the energy of an electron is going to depend upon "which box it is sitting in"
and what the energy of that box is. The lower the box (the closer it is to the nucleus) the lower (more negative) the energy and the more tightly an electron in that box is held.
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Although the major shell primarily determines the energy of an electron, there are minor differences between the energies of the subshells within any major shell, particularly in an atom with
more than one electron (actually, any atom other than hydrogen):s subshells are the lowest energy subshell within a shell,p subshells are next lowest,d subshells are higher than p subshells and f
subshells are higher than d subshells
Once we have many electrons (which means many shells and subshells) in an atom, we begin to see some overlap of subshells--particularly, the s subshell from the fourth level (4s) overlaps with
the d subshell from the third level (3d) such as shown below:
Shapes of the subshells:For many reasons, we cannot define exactly where an electron is within an atom. We must, instead, define the volume which will most likely contain electron density.
Consequently, the shapes of those volumes which can contain electron density are somewhat "fuzzy". We can depict volumes of high electron density (many dots) or volumes of low electron
density (few dots), as shown in the diagrams below. s subshell orbitals are always spherical--like beach balls,p subshell orbitals are dumbbell shaped;all three p orbitals within any p subshell are
the same except for their orientation on the x,y,z axes,d subshell orbitals have different shapes, as do f subshell orbitals. I have included a diagram of the d subshell orbitals for your
information, but I only want you to know the shapes of the s and p subshell orbitals
Cross-sections of an s-subshell orbital
15 | P a g e
A spherical s subshell orbital with high (very blue) and decreasing (less blue) electron density
All s subshell orbitals are spherical, the main difference; between different major shells is in the size of the sphere
Electron density model p subshell orbitals
d subshell orbitals:Electron Configurations are a particular arrangement or distribution of electrons among different subshells and shells within an atom.
Pattern:1s2
2s2
2p6
3s2
3p6
4s2
3d10
4p6
5s2
4d10
5p6
6s2
5d10
6p6
;lower energy higher energy ;strongest held e-
less tightly held e-
;You can see this pattern emerging from the energy levels in the
diagrams above.Symbols:the letters refer to the type of subshell s, p, d or f;the coefficients (numbers) to the left of each letter represent which major shell 1, 2, 3, etc.the subscript numbers
represent the number of electrons present in the subshell.Pauli Exclusion Principle: an orbital can contain no more than two electrons and those two electrons must be paired, in other words,
they must have opposite spin (usually indicated by one up-arrow and one down-arrow, as we will see shortly).Hund’s Rule: in a subshell where there are multiple orbitals with the same energy,
electrons will enter the each orbital singly until all orbitals are half filled before pairing with other electrons in the subshell.Orbital Diagrams: For ground state electron configurations, electrons
enter the electron configuration (orbital diagram) pattern beginning at the lowest energy and filling the pattern to the highest energy while obeying the Pauli Exclusion Principle and Hund’s
Rule.Examples: Orbital Diagrams or Electron Configurations for: H, He Row 1.Orbital Diagrams or Electron Configurations for: Li, Be, B, N, F, Ne Row 2:
16 | P a g e
Below are shown electronic configurations for the above elements in three forms of symbolism:
I Complete Electron Configuration
II Shorthand Electron Configuration
III Shorthand Valence Electron Configuration
I II III
Periodic Table Row 1:
1H 1H 1s1
1H 1s1
1s
2He  2He 1s2
2He 1s2
1s
Periodic Table Row 2:
3Li  3Li 1s2
2s1
3Li [He] 2s1
1s 2s
4Be   4Be 1s2
2s2
4Be [He] 2s2
1s 2s
5B   5B 1s2
2s2
2p1
5B [He] 2s2
2p1
1s 2s 2p
6C  6C 1s2
2s2
2p2
6C [He] 2s2
2p2
1s 2s 2p
7N 7N 1s2
2s2
2p3
7N [He] 2s2
2p3
1s 2s 2p
8O   8O 1s2
2s2
2p4
8O [He] 2s2
2p4
1s 2s 2p
9F    9F 1s2
2s2
2p5
9F [He] 2s2
2p5
1s 2s 2p
17 | P a g e
10Ne    10Ne 1s2
2s2
2p6
10Ne [He] 2s2
2p6
1s 2s 2p
Please Notice:When filling a set of orbitals in the same subshell which have equivalent energies (such as the p subshell orbitals in nitrogen), each electron occupies a different orbital until the set
of three orbitals is half-filled, then, and only then, do the electrons occupy the orbitals doubly and then only in the paired state (one arrow up, the other arrow down).The complete electron
configuration pattern (I) shows all electrons in the atom as arrows entered into the appropriate orbitals, in the appropriate state (up or down).The shorthand electron configuration pattern (II)
shows the number of all electrons in the atom as grouped superscripts of each subshell--it does not show the relative position or structure of electrons within a subshell.Please notice the blue
letters in (II), they are the inner core electrons which have the same configuration for all elements in the second row (and also happen to be the same configuration of the previous noble gas, He)
.The valence electrons are very special--they are the electrons in the outer most major shell. It is these electrons, and their structure, which primarily determine the chemical reactivity of atoms,
as we shall soon see.Notice that in the valence electron configuration patterns (III) of row 2 elements, the inner core electrons (in blue) are represented by the noble gas element at the end of row
1, which has the exact same configuration of electrons as those of the inner core.For row 3 elements, the inner core electrons are represented by the noble gas element at the end of row 2, as you
shall see--read further!Periodic Table Row 3:
11Na    11Na 1s2
2s2
2p6
3s1
11Na [Ne] 3s1
1s 2s 2p 3s
12Mg   12Mg 1s2
2s2
2p6
3s2
12Mg [Ne] 3s2
1s 2s 2p 3s
13Al   13Al 1s2 2s2
2p6
3s2
3p1
13Al [Ne] 3s2
3p1
1s 2s 2p 3s 3p
14Si     14Si 1s2
2s2
2p6
3s2
3p2
14Si [Ne] 3s2
3p2
1s 2s 2p 3s 3p
15P    15P 1s2
2s2
2p6
3s2
3p3
15P [Ne] 3s2
3p3
1s 2s 2p 3s 3p
16S    16S 1s2 2s2
2p6
3s2
3p4
16S [Ne] 3s2
3p4
1s 2s 2p 3s 3p
17Cl    17Cl 1s2
2s2
2p6
3s2
3p5
17Cl [Ne] 3s2
3p5
1s 2s 2p 3s 3p
18Ar   18Ar 1s2
2s2
2p6
3s2
3p6
18Ar [Ne] 3s2
3p6
1s 2s 2p 3s 3p
Once again, please notice that the configurations in blue are the inner or core electrons (represented by the noble gas element of that configuration, Ne for row 3 elements) and the
configurations in pink are the valence electrons. The electron configurations of the valence electrons are very important.Now, let's compare the electron configurations (complete and valence) of
elements in a group, say, group IA:
18 | P a g e
3Li 3Li [He] 2s1
1s 2s
11Na   11Na [Ne] 3s1
1s 2s 2p 3s
19K     19K [Ar] 4s1
1s 2s 2p 3s 3p 4s
Well, I think you can see the pattern. Within a group, elements have very similar valence electron configurations--same number of electrons in the same type of subshells but the only difference
is in the major shell. What other similarities do elements in the same group exhibit? (see chapter four on the periodic table).PERIODICITY:Notice that in the orbital diagrams above the outer
electrons of elements in the same group are similar: the same number of electrons, in the same types of orbitals but in different major shells.This type of periodicity can be used to quickly
determine the electron configuration or orbital diagram of any element based upon its position in the periodic table.Valence Electrons and Valence Shells:the most important electrons in an
atom are those on the outer-most edge of the atom (the outer major shell) – they come into contact with other atoms first and participate fully in reactions – they are the valence electrons
.valence shells contain the valence electrons.
Examples:10Ne 1s2
2s2
2p6 valence shell containing the maximum number of electrons
,11Na 1s2
2s2
2p6
3s1 valence shell containing one valence electron
,13Al 1s2
2s2
2p6
3s2
3p1 valence shell containing three valence electrons
Note:s-block Group IA and IIA
valence electrons are in the ns subshell where 'n' denotes the major shell or row
p-block Group IIIA - VIIIA
valence electrons are in the ns and np subshell where 'n' denotes the major shell or row
d-block Group IB - VIIIB (Transition Metals)
valence electrons are in the ns and (n-1)d subshell
f-block Inner Transition Metals sometimes called the lanthanides & the actinides
valence electrons are in the ns and (n-2)d subshell
PERIODIC PROPERTIES:Many physical properties depend upon the electronic properties of the atoms. Since the valence electronic structures are periodic, those physical properties also
reflect that periodicity. Properties such as atomic and ionic radii and ionization energy are periodic and can be predicted based upon an atoms relative position in the periodic table.Atomic
Size:atoms increase in size as the number of shells increase—in other words, as the valence electrons occupy larger shells;the atoms become larger going down a groupatoms decrease in size as
electrons are added to the same shell—in other words, the atoms become smaller across the periodic table from left to right, due to the contraction effect.As more electrons and protons are
added to the same shell (as you move from atoms on the left to atoms on the right), the attraction between positive and negative increases and the size of the shell is contracted.Ionic Size:positive
ions are smaller than the atoms from which they are derived.the greater the size of the positive charge, the smaller size of the ion relative to the atom.negative ions are larger than the atoms
from which they are derived.the greater the size of the negative charge, the larger the size of the ion relative to the atom;a series of isoelectronic ions (different ions with the same number of
electrons) such as those below, are not the same size
19 | P a g e
Ionization Energy:ionization energy is the energy required to remove an electron in the formation of an ion—the more difficult it is to remove an electron, the greater the ionization
energy.smaller atoms have greater ionization energy since the valence electrons are closer to the nucleus and more strongly attracted and, therefore, more difficult to remove;ionization energy
increases going up a group and across a row in the periodic table.
CHAPTER 2 :ELEMENTS AND ATOMS: MENDELEEV’S FIRST PERIODIC TABLE
Dmitrii Mendeleev (1834-1907; in Chemical Achievers at the Chemical Heritage Foundation) was born in Tobolsk, in Western Siberia. His chief contribution to chemistry was the establishment
of the periodic system of elements. Mendeleev was one of a number of independent discoverers of the periodic law in the 1860s--that number ranging from one [Leicester 1948] to six [van
Spronsen 1969] depending on the criteria one adopts. Mendeleev's formulation was clearly superior in several respects to the work of contemporary classifiers: it was the clearest, most
consistent, and most systematic formulation, and Mendeleev made several testable predictions based on it. It was not, however, free from error. Scientists, even great scientists, trying to see
further than others have in the past, do not always see the whole picture clearly. As noted below, Mendeleev himself corrected some of the errors within a few years; others persisted well into
the 20th
century.This table and the accompanying observations were first presented to the Russian Chemical Society in March 1869. (Actually, Mendeleev was ill, and his colleague Nikolai
Menshutkin presented his paper [Menschutkin 1934].) The paper was published in the first volume of the new society's journal. That same year, a German abstract of the paper, consisting of
the table and eight comments, was published in Zeitschrift für Chemie. The German abstract was the vehicle by which Mendeleev's ideas reached chemists working in Western Europe. An
English translation of that German abstract is presented here. View a On the Relationship of the Properties of the Elements to their Atomic Weights.D. Mendelejeff, Zeitschrift für Chemie 12,
405-406 (1869); translation by Carmen Giunta.By ordering the elements according to increasing atomic weight in vertical rows so that the horizontal rows contain analogous elements,[1] still
ordered by increasing atomic weight, one obtains the following arrangement, from which a few general conclusions may be derived
20 | P a g e
H=1[5]
Be=9,4 Mg=24
B=11 Al=27
C=12 Si=28
N=14 P=31
Li=7
The elements, if
arranged
according to
their atomic wei
21 | P a g e
, exhibit an evident stepwise variation [12] of properties. Chemically analogous
elements have either similar atomic weights [13] (Pt, Ir, Os), or weights which
increase by equal increments (K, Rb, Cs).[14] The arrangement according to
atomic weight corresponds to the valence [15] of the element and to a certain extent
the difference in chemical behavior, for example Li, Be, B, C, N, O, F. The elements
distributed most widely in nature have small atomic weights [16], and all such
elements are marked by the distinctness of their behavior. They are, therefore, the
representative elements; and so the lightest element H is rightly chosen as the most
representative. The magnitude of the atomic weight determines the properties of
the element. Therefore, in the study of compounds, not only the quantities and
properties of the elements and their reciprocal behavior are to be taken into
consideration, but also the atomic weight of the elements. Thus the compounds of S
and Tl [sic--Te was intended], Cl and J, display not only analogies, but also striking
differences.[17] One can predict the discovery of many new elements, for example
analogues of Si and Al with atomic weights of 65-75.[18] .A few atomic weights will
probably require correction; for example Te cannot have the atomic weight 128,
but rather 123-126.[19] .From the above table, some new analogies between
elements are revealed. Thus Bo (?) [Sic--apparently Ur was intended] appears as an
analogue of Bo and Al, as is well known to have been long established
experimentally. (Russian Chemical Society 1, 60); Notes: [1] the principle of
periodicity is apparent in this first sentence: repetition of chemical properties in a
series of elements arranged by atomic weight. Note also the cosmetic difference
between Mendeleev's layout and that of modern tables, which order the elements in
horizontal rows such that families of elements appear in vertical columns.
Mendeleev would use the latter sort of layout before long [Mendeleev 1871]. [2]This
table contains several implicit predictions of unknown elements. Mendeleev soon
retreated from this prediction of a heavier analogue of titanium and zirconium. His
later tables [Mendeleev 1871] erroneously placed lanthanum in this spot. This
original prediction was actually borne out in 1923 with the discovery of
hafnium.[3]Rhodium (Rh) is misplaced. It belongs between ruthenium (Ru) and
palladium (Pd). Technetium (Tc), the element which belongs between ruthenium
and molybdenum (Mo) has no stable isotopes and was not synthesized until
1937.[4]Most of the elements in this column are slightly out of order. After tungsten
(W) should come rhenium (Re), which was not yet discovered, followed by osmium
(Os), iridium (Ir), platinum (Pt), gold (Au), mercury (Hg), thallium (Tl), lead (Pb),
and bismuth (Bi). Bismuth, however, is placed correctly insofar as it completes the
row beginning with nitrogen (N). At this time, lead was frequently miscategorized,
placed among elements which form compounds with one atom of oxygen (PbO
analogous to CaO, for example); however, lead also forms a compound with two
atoms of oxygen (PbO2 analogous to CO2) and it belongs in the same group as
carbon (C). Similarly, thallium was often placed among elements which form
compounds with one atom of chlorine (TlCl analogous to NaCl, for example);
however, thallium also forms a compound with three atoms of chlorine (TlCl3
analogous to BCl3) and it belongs in the same group as boron (B).[5]The
classification of hydrogen has been an issue throughout the history of periodic
systems. Some tables place hydrogen with the alkali metals (lithium, sodium, etc.),
some with the halogens (fluorine, chlorine, etc.), some with both, and some in a box
of its own detached from the main body of the table. Mendeleev's original table did
none of the above, placing it in the same row as copper, silver, and mercury.[6]The
prediction of an unknown analogue of aluminum was borne out by the discovery in
1875 of gallium (atomic weight = 70), the first of Mendeleev's predictions to be so
confirmed. [Lecoq de Boisbaudran 1877][7]Uranium (standard symbol U) is
misplaced. Its atomic weight is actually more than double the value given here. The
element which belongs between cadmium (Cd) and tin (Sn) is.indium (In), and
Mendeleev put indium there in the next version of his table [Mendeleev 1871]. The
proper place for uranium, however, would not be found until the 1940s.[8]The
prediction of an unknown analogue of silicon was borne out by the discovery in
1886 of germanium (atomic weight = 73). [Winkler 1886][9]In German
publications, J is frequently used instead of I as the chemical symbol for iodine
(Jod, in German). Iodine is placed correctly after tellurium (i.e., with the halogens)
despite having a lower atomic weight than tellurium. See comment 7 after the
table.[10]The prediction of an unknown element following calcium is a weak
version of Mendeleev's subsequent prediction of the element we now know as
scandium, discovered in 1879 [Nilson 1879]. In Mendeleev's 1871 table [Mendeleev
1871] the missing element is correctly placed between calcium and titanium, and as
an analogue of yttrium. That the 1869 prediction is flawed can be seen from the
fact that every other entry in the bottom reaches of the table is wrong. (See next
note.) Still, the prediction deserves more credit than van Spronsen gave it [van
Spronsen 1969, p. 220]: "That the element next to calcium later proved to be
scandium was fortuitous; Mendeleev cannot be said to have already foreseen this
element in 1869."
22 | P a g e
[11]The elements placed in the last four rows of the table puzzled Mendeleev, as is
apparent from the glut of question marks and the fact that several are out of order
according to their assigned atomic weights. Many of these elements were rare and
poorly characterized at the time. Didymium appeared in many lists of elements at
this time, but it was later proved to consist of two elements, praseodymium and
neodymium. The atomic weights of erbium, yttrium (standard symbol Y), indium,
cerium, lanthanum, and thorium are wrong. The interdependence of atomic
weights and chemical formulas that plagued determinations of atomic weight since
the time of Dalton was still problematic for these elements. Most of them elements
(erbium, yttrium, cerium, lanthanum, and the component elements of didymium)
belong to the family of rare earths, a group whose classification would present
problems for many years to come. (Thorium belongs to the group of elements
immediately below most of the rare earths.) Many of the rare earths were not yet
discovered, and (as already noted) the atomic weights of the known elements were
not well determined. The chemical properties of the rare earths are so similar that
they were difficult to distinguish and to separate. Mendeleev made some progress
with these elements in the next couple of years. His 1871 table [Mendeleev 1871]
has correct weights for yttrium, indium, cerium, and thorium, and correct
classification for yttrium and indium.[12]Translator's note: In his 1889 Faraday
lecture [Mendeleev 1889], Mendeleev used the word "periodicity" rather than the
phrase "stepwise variation" in translating this sentence from his 1869 paper.
"Periodicity" is certainly an appropriate term to describe the cyclic repetition in
properties evident in this arrangement. It is worth noting, however, that the
German words read in 1869 by Western European scientists (stufenweise
Abänderung) lack the implication of repetition inherent in the term periodicity. --
CJG [13]Groups of similar elements with consecutive atomic weights are a little-
emphasized part of classification systems from Mendeleev's time and before (cf.
Newlands 1864) to the present.[14]The existence of a very regular progression in
atomic weight among elements with similar chemical behavior had attracted the
attention of chemists almost from the time they began to measure atomic weights
[Döbereiner 1829]. The triad of elements Mendeleev cites here includes two
(rubidium and cesium) discovered in the early 1860s. Mendeleev's table, however,
goes beyond strictly regular isolated triads of elements to a systematic classification
(albeit not always correct) of all known elements. [15]The valence of an element is
essentially the number of bonds that element can make when it forms compounds
with other elements. An atom of hydrogen, for example, can make just one bond, so
its valence is one; we call it monovalent. An atom of oxygen can bond with two
atoms of hydrogen, so its valence is two. Some elements, particularly heavier
elements, have more than one characteristic valence. (For example, lead has
valence 2 and 4; thallium has valence 1 and 3. See note 4 above.) The elements in
the cited series have valences 1, 2, 3, 4, 3, 2, and 1 respectively.[16]Mendeleev is
correct in this observation. The two lightest elements, hydrogen and helium (the
latter as yet unknown) are the most common elements in the universe, making up
the bulk of stars. Oxygen and silicon are the most common elements in the earth's
crust. Iron is the heaviest element among the most abundant elements in the stars
and the earth's crust.[17]Although the chemical behavior of elements in the same
family is similar, it is not identical: there are differences due to the difference in
atomic weight. For example, both chlorine and iodine form compounds with one
atom of hydrogen: HCl and HI. These compounds are similar, in that they are both
corrosive gases which dissolve readily in water. But they differ in that HI has, for
example, a higher boiling point and melting point than HCl (typical of the heavier
of a pair of related compounds).[18]In later publications [Mendeleev 1871]
Mendeleev went into considerable detail regarding the properties of predicted
elements. The success of these predictions played a part in establishing the periodic
system, although apparently not the primary part. [Brush 1996] See Scerri &
Worrall 2001 for a discussion of prediction and accommodation in the periodic
table. [19]Mendeleev went on to incorporate this "correction" in his 1871 table
[Mendeleev 1871], listing the atomic weight of tellurium as 125. But the
"correction" is erroneous. Mendeleev was right to put tellurium in the same group
with sulfur and oxygen; however, strict order of atomic weights according to the
best information he had available would have required iodine (127) to come before
tellurium (128). He was suspicious of this apparent inversion of atomic weight
order; as it happens, the atomic weights Mendeleev had available to him agree with
the currently accepted values.While his suggestion to change that of tellurium was
wrong, his classification was correct and his faith in the regularity of the periodic
system was only slightly misplaced. The natural order of the elements is not quite
one of increasing atomic weight, but one of increasing atomic number. In 1913, a
discovery by Henry Moseley made the atomic number more than simply a rank
order for the elements [Moseley 1913, 1914]. The atomic number is the same as the
quantity of positive charge in the nucleus of an atom. The periodic system contains
a few "inversions" of atomic weight, but no inversions of atomic
number.References: Stephen G. Brush, "The Reception of Mendeleev's Periodic
Law in America and Britain," Isis 87 595-628 (1996) ;Johann Döbereiner,
Poggendorf's Annalen der Physik und Chemie 15, 301-307 (1829); translated as "An
Attempt to Group Elementary Substances according to Their Analogies," in Henry
M. Leicester & Herbert S. Klickstein, eds., A Source Book in Chemistry, 1400-1900
(Cambridge,
23 | P a g e
When a new entry-level textbook in chemistry comes out, the obvious first question
is ―Why?‖ Why write another book when there are other texts available? .Actually,
we had two main reasons. First, of all the textbooks that are available for a one-
semester general chemistry, organic chemistry, and biochemistry (GOB) course,
virtually all are single-author textbooks. Why this one stands out—and, we would
argue, why this textbook might be preferable—is that the author team is composed
of chemistry faculty who specialize in the G part, the O part, and the B part. One
of us (DWB) is a physical chemist who spends a lot of time in the general chemistry
sequence, whether for nonscience majors, health profession majors, or science and
engineering majors. Another author (JWH) is an organic chemist by training and
an experienced textbook author, while the third author (RJS) is a biochemistry
professor and also a successful textbook author. All three authors are experienced,
successful teachers. Thus, right from the start, this author team brings the
appropriate experience and expertise that can combine to write a superior textbook
for this market.The second reason was the opportunity presented by the unique
publishing strategy of Flat World Knowledge. The entire author team is excited
about the potential for online presentation of content in this Internet age. In
addition to having the content online, print copies of the textbook are readily
available, as are individual chapters, vocabulary cards, exercise solutions, and
other products. The easy availability of these items maximizes the ability of
students to customize their personal tools, increasing their chances for success in a
one-semester chemistry course.This textbook is intended for the one-semester GOB
course. Although a two-semester GOB sequence is available at many colleges and
universities, one-semester GOB offerings are increasing in popularity. The need to
cover so many topics in one semester or quarter places additional pressure on the
tools used to teach the course, and the authors feel that a textbook developed
explicitly for the one-semester course will provide students with a superior
educational experience. Many one-semester GOB courses employ either a
rewritten, watered-down two-semester textbook or a bona fide two-semester
textbook with cherry-picked topics. In the opinion of this author team, neither
choice provides students with the best learning experience. This textbook does not
have a two-semester counterpart. It was developed specifically for the one-semester
GOB course. As such, the chapters are short and succinct, covering the
fundamental material and leaving out the extraneous. We recognize that students
taking this particular course are likely interested in health professions, such as
nursing, occupational therapy, physical therapy, physician assistance, and the like.
As such, we have focused certain examples and textbook features on these areas so
students realize from the beginning how these basic chemistry topics apply to their
career choice.This textbook is divided into approximately one-half general
chemistry topics, one-fourth organic chemistry topics, and one-fourth biochemistry
topics. We feel that these fractions provide the appropriate mix of chemistry topics
for most students’ needs. The presentation is standard: there is no attempt to
integrate organic and biological chemistry throughout a general chemistry
textbook, although there is an early introduction to organic chemistry so that
carbon-containing compounds can be included as soon as possible. The first
chapter stands out a bit for covering a relatively large amount of material, but that
is necessary. There is a certain skill set that students must have to be successful in
any GOB course, and rather than relegate these skills to an appendix that is too
often overlooked, the first chapter covers them explicitly. Some of these topics can
be omitted at the instructor’s discretion.The G part of the textbook then continues
into atoms and molecules, chemical reactions, simple stoichiometry, energy, the
phases of matter, solutions, and acids and bases (including a short treatment of
equilibrium) and then ends with nuclear chemistry. The O part of the textbook
starts with hydrocarbons and quickly covers aromatic compounds and the basic
functional groups, focusing on those functional groups that have specific
applications in biochemistry. The B part starts by immediately applying the
organic knowledge to carbohydrates and other biologically important compounds.
This section ends with a chapter on metabolism, which is, after all, the ultimate
goal for a textbook like this—a discussion of the chemistry of life.Each chapter is
filled with example problems that illustrate the concepts at hand. In the
mathematical exercises, a consistent style of problem solving has been used. We
understand that there may be more than one way to solve a mathematical problem,
but having a consistent problem-solving style increases the chance for student
comprehension. Particular emphasis is placed on the units of quantities and how
they have to work out appropriately in algebraic treatments. For each example
problem, there is a Skill-Building Exercise immediately following that will help
students practice the very same concept but without an elaborate answer worked
out.Every section of each chapter starts with one or more Learning Objectives that
preview the section. These Learning Objectives are echoed at the end of each
section with Key Takeaways as well as Concept Review Exercises that ask about
the main ideas of the section. Sections then end with a set of exercises that students
can use to immediately put the knowledge of that section into practice. Most of the
exercises are paired, so that students can work two similar exercises for additional
practice. Finally, Additional Exercises at the end of each chapter ask more
challenging questions, bring multiple concepts together into a single exercise, or
extend the chapter concepts to broader perspectives. The complete exercise
portfolio of the textbook—Skill-Building Exercises, Concept Review Exercises,
end-of-section exercises, and Additional Exercises—provides multiple
opportunities for students to practice the content.
24 | P a g e
Other features in the textbook include Looking Closer, a chance to expand on a
topic more than a typical textbook would. We have selected topics that are relevant
and should appeal to students at this level. There are essays titled To Your Health
that focus on how some of the topics relate directly to health issues—the focus of
most of the students in this course. Do students realize that the simple act of
breathing, something most of us do without thinking, is a gas law in action? Most
chapters also have a Career Focus that presents an occupation related to the health
professions. Students at this level may not know exactly what they want to do in the
health professions, so having these essays gives some information about the career
possibilities awaiting them.These features are kept to a minimum, however; this is
a one-semester textbook covering general chemistry, organic chemistry, and
biochemistry. We recognize that users appreciate features like this, but we also
recognize the need to focus on the core chemistry content. We hope we have
reached an appropriate balance with the amount of additional features.We hope
that this textbook meets your and your students’ goals.David W. Ball,John W. Hill
and Rhonda J. Scott:February 2011
CHAPTER 21 :APPENDIX: PERIODIC TABLE OF THE ELEMENTS
In this chapter, we present some data on the chemical elements. The periodic table
lists all the known chemical elements, arranged by atomic number (that is, the
number of protons in the nucleus). The periodic table is arguably the best tool in all
of science; no other branch of science can summarize its fundamental constituents
in such a concise and useful way. Many of the physical and chemical properties of
the elements are either known or understood based on their positions on the
periodic table. Periodic tables are available with a variety of chemical and physical
properties listed in each element’s box. What follows here is a relatively simple
version. The Internet is a great place to find periodic tables that contain additional
information.One item on most periodic tables is the atomic mass of each element.
For many applications, only one or two decimal places are necessary for the atomic
mass. However, some applications (especially nuclear chemistry; see ) require more
decimal places. The atomic masses in represent the number of decimal places
recognized by the International Union of Pure and Applied Chemistry, the
worldwide body that develops standards for chemistry. The atomic masses of some
elements are known very precisely, to a large number of decimal places. The
atomic masses of other elements, especially radioactive elements, are not known as
precisely. Some elements, such as lithium, can have varying atomic masses
depending on how their isotopes are isolated.The web offers many interactive
periodic table resources. For example, see
Table 21.1 the Basics of the Elements of the Periodic Table
25 | P a g e
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32 | P a g e
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33 | P a g e
*Element has no stable nuclides. However, three such elements (Th, Pa, and U) have
a characteristic terrestrial isotopic composition, and for these an atomic mass is
tabulated.
Commercially available Li materials have atomic weights that range between 6.939
and 6.996; if a more accurate value is required, it must be determined for the
specific material.
g Geological specimens are known in which the element has an isotopic composition
outside the limits for normal material. The difference between the atomic mass of
the element in such specimens and that given in the table may exceed the stated
uncertainty.
Modified isotopic compositions may be found in commercially available material
because it has been subjected to an undisclosed or inadvertent isotopic fractionation.
Substantial deviations in the atomic mass of the element from that given in the table
can occur.
Range in isotopic composition of normal terrestrial material prevents a more precise
Ar(E) being given; the tabulated Ar(E) value and uncertainty should be applicable to
normal material.
CHAPTER 20: ENERGY METABOLISM
The discovery of the link between insulin and diabetes led to a period of intense
research aimed at understanding exactly how insulin works in the body to regulate
glucose levels. Hormones in general act by binding to some protein, known as the
hormone’s receptor, thus initiating a series of events that lead to a desired outcome.
In the early 1970s, the insulin receptor was purified, and researchers began to
study what happens after insulin binds to its receptor and how those events are
linked to the uptake and metabolism of glucose in cells.The insulin receptor is
located in the cell membrane and consists of four polypeptide chains: two identical
chains called α chains and two identical chains called β chains. The α chains,
positioned on the outer surface of the membrane, consist of 735 amino acids each
and contain the binding site for insulin. The β chains are integral membrane
proteins, each composed of 620 amino acids. The binding of insulin to its receptor
stimulates the β chains to catalyze the addition of phosphate groups to the specific
side chains of tyrosine (referred to as phosphorylation) in the β chains and other
cell proteins, leading to the activation of reactions that metabolize glucose. In this
chapter we will look at the pathway that breaks down glucose—in response to
activation by insulin—for the purpose of providing energy for the cell.Figure 20.1
Model of the Structure of the Insulin Receptor
Life requires energy. Animals, for example, require heat energy to maintain body
temperature, mechanical energy to move their limbs, and chemical energy to
synthesize the compounds needed by their cells. Living cells remain organized and
functioning properly only through a continual supply of energy. But only specific
forms of energy can be used. Supplying a plant with energy by holding it in a flame
will not prolong its life. On the other hand, a green plant is able to absorb radiant
energy from the sun, the most abundant source of energy for life on the earth.
Plants use this energy first to form glucose and then to make other carbohydrates,
as well as lipids and proteins. Unlike plants, animals cannot directly use the sun’s
energy to synthesize new compounds. They must eat plants or other animals to get
carbohydrates, fats, and proteins and the chemical energy stored in them (). Once
digested and transported to the cells, the nutrient molecules can be used in either of
two ways: as building blocks for making new cell parts or repairing old ones or
―burned‖ for energy.Figure 20.2 Some Energy Transformations in Living Systems
34 | P a g e
Plants and animals exist in a cycle; each requires products of the other.The
thousands of coordinated chemical reactions that keep cells alive are referred to
collectively as metabolism. In general, metabolic reactions are divided into two
classes: the breaking down of molecules to obtain energy is catabolism, and the
building of new molecules needed by living systems is anabolism.Note:Any
chemical compound that participates in a metabolic reaction is a metabolite.Most of
the energy required by animals is generated from lipids and carbohydrates. These
fuels must be oxidized, or ―burned,‖ for the energy to be released. The oxidation
process ultimately converts the lipid or carbohydrate to carbon dioxide (CO2) and
water (H2O).Carbohydrate: C6H12O6 + 6O2 → 6CO2 + 6H2O + 670 kcal Lipid:
C16H32O2 + 23O2 → 16CO2 + 16H2O + 2,385 kcal .These two equations summarize
the biological combustion of a carbohydrate and a lipid by the cell through
respiration. Respiration is the collective name for all metabolic processes in which
gaseous oxygen is used to oxidize organic matter to carbon dioxide, water, and
energy.Like the combustion of the common fuels we burn in our homes and cars
(wood, coal, gasoline), respiration uses oxygen from the air to break down complex
organic substances to carbon dioxide and water. But the energy released in the
burning of wood is manifested entirely in the form of heat, and excess heat energy
is not only useless but also injurious to the living cell. Living organisms instead
conserve much of the energy respiration releases by channeling it into a series of
stepwise reactions that produce adenosine triphosphate (ATP) or other compounds
that ultimately lead to the synthesis of ATP. The remainder of the energy is
released as heat and manifested as body temperature. Examines the structure of
ATP and begins to explore its role as the chemical energy carrier of the body.1.5
Expressing Numbers: Significant Figures
Learning Objectives:Identify the number of significant figures in a reported
value.Use significant figures correctly in arithmetical operations.Scientists have
established certain conventions for communicating the degree of precision of a
measurement. Imagine, for example, that you are using a meterstick to measure the
width of a table. The centimeters (cm) are marked off, telling you how many
centimeters wide the table is. Many metersticks also have millimeters (mm)
marked off, so we can measure the table to the nearest millimeter. But most
metersticks do not have any finer measurements indicated, so you cannot report
the table’s width any more exactly than to the nearest millimeter. All you can do is
estimate the next decimal place in the measurement ().
Figure 1.7 Measuring an Object to the Correct Number of Digits
35 | P a g e
How many digits should be reported for the length of this object?.The concept of
significant figures takes this limitation into account. The significant figures of a
measured quantity are defined as all the digits known with certainty and the first
uncertain, or estimated, digit. It makes no sense to report any digits after the first
uncertain one, so it is the last digit reported in a measurement. Zeros are used
when needed to place the significant figures in their correct positions. Thus, zeros
may not be significant figures.Note:―Sig figs‖ is a common abbreviation for
significant figures.For example, if a table is measured and reported as being 1,357
mm wide, the number 1,357 has four significant figures. The 1 (thousands), the 3
(hundreds), and the 5 (tens) are certain; the 7 (units) is assumed to have been
estimated. It would make no sense to report such a measurement as 1,357.0 or
1,357.00 because that would suggest the measuring instrument was able to
determine the width to the nearest tenth or hundredth of a millimeter, when in fact
it shows only tens of millimeters and the units have to be estimated.On the other
hand, if a measurement is reported as 150 mm, the 1 (hundreds) and the 5 (tens)
are known to be significant, but how do we know whether the zero is or is not
significant? The measuring instrument could have had marks indicating every 10
mm or marks indicating every 1 mm. Is the zero an estimate, or is the 5 an estimate
and the zero a placeholder?.The rules for deciding which digits in a measurement
are significant are as follows:All nonzero digits are significant. In 1,357, all the
digits are significant.Captive (or embedded) zeros, which are zeros between
significant digits, are significant. In 405, all the digits are significant.Leading zeros,
which are zeros at the beginning of a decimal number less than 1, are not
significant. In 0.000458, the first four digits are leading zeros and are not
significant. The zeros serve only to put the digits 4, 5, and 8 in the correct positions.
This number has three significant figures.Trailing zeros, which are zeros at the end
of a number, are significant only if the number has a decimal point. Thus, in 1,500,
the two trailing zeros are not significant because the number is written without a
decimal point; the number has two significant figures. However, in 1,500.00, all six
digits are significant because the number has a decimal point.Example 8;How
many significant digits does each number
have?;6,798,000,6,000,798,6,000,798.00,0.0006798;Solution:four (by rules 1 and
4),seven (by rules 1 and 2),nine (by rules 1, 2, and 4),four (by rules 1 and 3),Skill-
Building Exercise;How many significant digits does each number
have?,2.1828,0.005505,55,050,5,500
Combining Numbers:It is important to be aware of significant figures when you
are mathematically manipulating numbers. For example, dividing 125 by 307 on a
calculator gives 0.4071661238… to an infinite number of digits. But do the digits in
this answer have any practical meaning, especially when you are starting with
numbers that have only three significant figures each? When performing
mathematical operations, there are two rules for limiting the number of significant
figures in an answer—one rule is for addition and subtraction, and one rule is for
multiplication and division.For addition or subtraction, the rule is to stack all the
numbers with their decimal points aligned and then limit the answer’s significant
figures to the rightmost column for which all the numbers have significant figures.
Consider the following:
The arrow points to the rightmost column in which all the numbers have
significant figures—in this case, the tenths place. Therefore, we will limit our final
answer to the tenths place. Is our final answer therefore 1,459.0? No, because when
we drop digits from the end of a number, we also have to round the number. Notice
that the second dropped digit, in the hundredths place, is 8. This suggests that the
answer is actually closer to 1,459.1 than it is to 1,459.0, so we need to round up to
1,459.1. The rules in rounding are simple: If the first dropped digit is 5 or higher,
round up. If the first dropped digit is lower than 5, do not round up.
For multiplication or division, the rule is to count the number of significant figures
in each number being multiplied or divided and then limit the significant figures in
the answer to the lowest count. An example is as follows:
36 | P a g e
The final answer, limited to four significant figures, is 4,094. The first digit
dropped is 1, so we do not round up.Scientific notation provides a way of
communicating significant figures without ambiguity. You simply include all the
significant figures in the leading number. For example, the number 450 has two
significant figures and would be written in scientific notation as 4.5 × 102
, whereas
450.0 has four significant figures and would be written as 4.500 × 102
. In scientific
notation, all significant figures are listed explicitly.Example 9;Write the answer for
each expression using scientific notation with the appropriate number of significant
figures.23.096 × 90.300,125 × 9.000,1,027 + 610 + 363.06:Solution:The calculator
answer is 2,085.5688, but we need to round it to five significant figures. Because the
first digit to be dropped (in the hundredths place) is greater than 5, we round up to
2,085.6, which in scientific notation is 2.0856 × 103
.The calculator gives 1,125 as the
answer, but we limit it to three significant figures and convert into scientific
notation: 1.13 × 103
.The calculator gives 2,000.06 as the answer, but because 610
has its farthest-right significant figure in the tens column, our answer must be
limited to the tens position: 2.0 × 103
.Skill-Building Exercise;Write the answer for
each expression using scientific notation with the appropriate number of significant
figures,217 ÷ 903,13.77 + 908.226 + 515,255.0 – 99,0.00666 × 321
Remember that calculators do not understand significant figures. You are the one
who must apply the rules of significant figures to a result from your
calculator.Concept Review Exercises;Explain why the concept of significant figures
is important in numerical calculations.State the rules for determining the
significant figures in a measurement.When do you round a number up, and when
do you not round a number up?.Answers;Significant figures represent all the
known digits of a measurement plus the first estimated one.All nonzero digits are
significant; zeros between nonzero digits are significant; zeros at the end of a
nondecimal number or the beginning of a decimal number are not significant;
zeros at the end of a decimal number are significant.Round up only if the first digit
dropped is 5 or higher.Key Takeaways;Significant figures properly report the
number of measured and estimated digits in a measurement.There are rules for
applying significant figures in calculations.Exercises;Define significant figures.
Why are they important?.Define the different types of zeros found in a number and
explain whether or not they are significant.How many significant figures are in
each number?,140,0.009830,15,050,221,560,000,5.67 × 103
,2.9600 × 10−5
.How many
significant figures are in each number?1.05,9,500,0.0004505,0.00045050,7.210 ×
106
,5.00 × 10−6
.Round each number to three significant
figures.34,705,34,750,34,570.Round each number to four significant
figures.34,705,0.00541098.90443 × 108
.Perform each operation and express the
answer to the correct number of significant figures.467.88 + 23.0 + 1,306 = ?.10,075
+ 5,822.09 − 34.0 = ?.0.00565 + 0.002333 + 0.0991 = ?.Perform each operation and
express the answer to the correct number of significant figures.0.9812 + 1.660 +
8.6502 = ?.189 + 3,201.8 − 1,100 = ?.675.0 − 24 + 1,190 = ?.Perform each operation
and express the answer to the correct number of significant figures.439 × 8,767 =
?,23.09 ÷ 13.009 = ?,1.009 × 876 = ?.Perform each operation and express the answer
to the correct number of significant figures.3.00 ÷ 1.9979 = ?,2,300 × 185 = ?,16.00
× 4.0 = ?.Use your calculator to solve each equation. Express each answer in proper
scientific notation and with the proper number of significant figures. If you do not
get the correct answers, you may not be entering scientific notation into your
calculator properly, so ask your instructor for assistance.
(5.6 × 103
) × (9.04 × 10−7
) = ?
(8.331 × 10−2
) × (2.45 × 105
) = ?
983.09 ÷ (5.390 × 105
) = ?
0.00432 ÷ (3.9001 × 103
) = ?
Use your calculator to solve each equation. Express each answer in proper
scientific notation and with the proper number of significant figures. If you do not
get the correct answers, you may not be entering scientific notation into your
calculator properly, so ask your instructor for assistance.
(5.2 × 106
) × (3.33 × 10−2
) = ?
(7.108 × 103
) × (9.994 × 10−5
) = ?
(6.022 × 107
) ÷ (1.381 × 10−8
) = ?
37 | P a g e
(2.997 × 108
) ÷ (1.58 × 1034
) = ?
Answers
Significant figures represent all the known digits plus the first estimated digit of a
measurement; they are the only values worth reporting in a measurement.
two
four
four
five
three
five
34,700
34,800
34,600
1,797
15,863
0.1071
3,850,000
1.775
38 | P a g e
884
5.1 × 10−3
2.04 × 104
1.824 × 10−3
1.11 × 10−6
Next
1.6 The International System of Units
Learning Objective
Recognize the SI base units and explain the system of prefixes used with them.
Now that we have discussed some of the conventions for expressing numbers, let us
focus on the other component of a quantity—the units.
People who live in the United States measure weight in pounds, height in feet and
inches, and a car’s speed in miles per hour. In contrast, chemistry and other
branches of science use the International System of Units (also known as SI after
Système Internationale d’Unités), which was established so that scientists around
the world could communicate efficiently with each other. Many countries have also
adopted SI units for everyday use as well. The United States is one of the few
countries that has not.
Base SI Units
Base (or basic) units, are the fundamental units of SI. There are seven base units,
which are listed in . Chemistry uses five of the base units: the mole for amount, the
kilogram for mass, the meter for length, the second for time, and the kelvin for
temperature. The degree Celsius (°C) is also commonly used for temperature. The
numerical relationship between kelvins and degrees Celsius is as follows:
K = °C + 273
Table 1.2 The Seven Base SI Units
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39 | P a g e
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Note
The United States uses the English system of units for many quantities. Inches, feet,
miles, gallons, pounds, and so forth, are all units connected with the English system
of units.
40 | P a g e
The size of each base unit is defined by international convention. For example, the
kilogram is defined as the quantity of mass of a special metal cylinder kept in a
vault in France (). The other base units have similar definitions. The sizes of the
base units are not always convenient for all measurements. For example, a meter is
a rather large unit for describing the width of something as narrow as human hair.
Instead of reporting the diameter of hair as 0.00012 m or even 1.2 × 10−4
m, SI also
provides a series of prefixes that can be attached to the units, creating units that
are larger or smaller by powers of 10.
Figure 1.8 the Kilogram
The standard for the kilogram is a platinum-iridium cylinder kept in a special
vault in France.
Source: Photo reproduced by permission of the Bureau International des Poids et
Mesures, who retain full internationally protected copyright.
Common prefixes and their multiplicative factors are listed in . (Perhaps you have
already noticed that the base unit kilogram is a combination of a prefix, kilo-
meaning 1,000 ×, and a unit of mass, the gram.) Some prefixes create a multiple of
the original unit: 1 kilogram equals 1,000 grams, and 1 megameter equals
1,000,000 meters. Other prefixes create a fraction of the original unit. Thus, 1
centimeter equals 1/100 of a meter, 1 millimeter equals 1/1,000 of a meter, 1
microgram equals 1/1,000,000 of a gram, and so forth.
Table 1.3 Prefixes Used with SI Units
41 | P a g e
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42 | P a g e
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43 | P a g e
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*The letter µ is the Greek lowercase letter for m and is called ―mu,‖ which is
pronounced ―myoo.‖
Both SI units and prefixes have abbreviations, and the combination of a prefix
abbreviation with a base unit abbreviation gives the abbreviation for the modified
unit. For example, kg is the abbreviation for kilogram. We will be using these
abbreviations throughout this book.
Derived SI Units
Derived units are combinations of SI base units. Units can be multiplied and
divided, just as numbers can be multiplied and divided. For example, the area of a
square having a side of 2 cm is 2 cm × 2 cm, or 4 cm2
(read as ―four centimeters
squared‖ or ―four square centimeters‖). Notice that we have squared a length unit,
the centimeter, to get a derived unit for area, the square centimeter.
45 | P a g e
Volume is an important quantity that uses a derived unit. Volume is the amount of
space that a given substance occupies and is defined geometrically as length ×
width × height. Each distance can be expressed using the meter unit, so volume has
the derived unit m × m × m, or m3
(read as ―meters cubed‖ or ―cubic meters‖). A
cubic meter is a rather large volume, so scientists typically express volumes in
terms of 1/1,000 of a cubic meter. This unit has its own name—the liter (L). A liter
is a little larger than 1 US quart in volume. ( gives approximate equivalents for
some of the units used in chemistry.) As shown in , a liter is also 1,000 cm3
. By
definition, there are 1,000 mL in 1 L, so 1 milliliter and 1 cubic centimeter
represent the same volume.
1 mL = 1 cm3
Figure 1.9 The Liter
A liter is defined as a cube 10 cm (1/10th of a meter) on a side. A milliliter,
1/1,000th of a liter, is equal to 1 cubic centimeter.
Table 1.4 Approximate Equivalents to Some SI Units
1 m ≈ 39.36 in. ≈ 3.28 ft ≈ 1.09 yd
1 cm ≈ 2.54 in.
1 km ≈ 0.62 mi
1 kg ≈ 2.20 lb
1 lb ≈ 454 g
1 L ≈ 1.06 qt
1 qt ≈ 0.946 L
Energy, another important quantity in chemistry, is the ability to perform work,
such as moving a box of books from one side of a room to the other side. It has a
derived unit of kg·m2
/s2
. (The dot between the kg and m units implies the units are
multiplied together.) Because this combination is cumbersome, this collection of
units is redefined as a joule (J). An older unit of energy, the calorie (cal), is also
widely used. There are 4.184 J in 1 cal. All chemical processes occur with a
simultaneous change in energy. (For more information on energy changes, see .)
To Your Health: Energy and Food
The food in our diet provides the energy our bodies need to function properly. The
energy contained in food could be expressed in joules or calories, which are the
conventional units for energy, but the food industry prefers to use the kilocalorie
and refers to it as the Calorie (with a capital C). The average daily energy
requirement of an adult is about 2,000–2,500 Calories, which is 2,000,000–2,500,000
calories (with a lowercase c).
46 | P a g e
If we expend the same amount of energy that our food provides, our body weight
remains stable. If we ingest more Calories from food than we expend, however, our
bodies store the extra energy in high-energy-density compounds, such as fat, and
we gain weight. On the other hand, if we expend more energy than we ingest, we
lose weight. Other factors affect our weight as well—genetic, metabolic, behavioral,
environmental, cultural factors—but dietary habits are among the most important.
In 2008 the US Centers for Disease Control and Prevention issued a report stating
that 73% of Americans were either overweight or obese. More alarmingly, the
report also noted that 19% of children aged 6–11 and 18% of adolescents aged 12–
19 were overweight—numbers that had tripled over the preceding two decades.
Two major reasons for this increase are excessive calorie consumption (especially
in the form of high-fat foods) and reduced physical activity. Partly because of that
report, many restaurants and food companies are working to reduce the amounts
of fat in foods and provide consumers with more healthy food options.
Density is defined as the mass of an object divided by its volume; it describes the
amount of matter contained in a given amount of space.
density=massvolume
Thus, the units of density are the units of mass divided by the units of volume:
g/cm3
or g/mL (for solids and liquids), g/L (for gases), kg/m3
, and so forth. For
example, the density of water is about 1.00 g/cm3
, while the density of mercury is
13.6 g/mL. (Remember that 1 mL equals 1 cm3
.) Mercury is over 13 times as dense
as water, meaning that it contains over 13 times the amount of matter in the same
amount of space. The density of air at room temperature is about 1.3 g/L.
Example 10
Give the abbreviation for each unit and define the abbreviation in terms of the base
unit.
kiloliter
microsecond
decimeter
nanogram
Solution
The abbreviation for a kiloliter is kL. Because kilo means ―1,000 ×,‖ 1 kL equals
1,000 L.
The abbreviation for microsecond is µs. Micro implies 1/1,000,000th of a unit, so 1
µs equals 0.000001 s.
The abbreviation for decimeter is dm. Deci means 1/10th, so 1 dm equals 0.1 m.
The abbreviation for nanogram is ng and equals 0.000000001 g.
Skill-Building Exercise
Give the abbreviation for each unit and define the abbreviation in terms of the base
unit.
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single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo
single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo

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Semelhante a single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo

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single drop of chemistry module for grade 9-12 student reference:by shemelis weisn east hararghe melka balo

  • 1. 1 | P a g e : “BE WISE FOR YOUR KNOWLEDGE AND A PLIED IT ON YOUR GENERATION”
  • 2. 2 | P a g e ACTIVITIES SUMMARY NOTES LABORATORY REPORT PRICE 56 .00 ETB
  • 3. 3 | P a g e TABLE OF CONTENTS ABOUT THE AUTHORS I ACKNOWLEDGEMENTS II PREFACE III CHEMISTRY, MATTER, AND MEASUREMENT 1 ELEMENTS, ATOMS, AND THE PERIODIC TABLE 10 IONIC BONDING AND SIMPLE IONIC COMPOUNDS 20 COVALENT BONDING AND SIMPLE MOLECULAR COMPOUNDS 30 INTRODUCTION TO CHEMICAL REACTIONS 40 QUANTITIES IN CHEMICAL REACTIONS 50 ENERGY AND CHEMICAL PROCESSES 60 SOLIDS, LIQUIDS, AND GASES 70 SOLUTIONS 80 ACIDS AND BASES 90 ARRHENIUS DEFINITION OF ACIDS AND BASES 100 BRØNSTED-LOWRY DEFINITION OF ACIDS AND BASES 110 WATER: BOTH AN ACID AND A BASE 120
  • 4. 4 | P a g e THE STRENGTHS OF ACIDS AND BASES 130 BUFFERS 130 END-OF-CHAPTER MATERIAL 140 NUCLEAR CHEMISTRY 150 ORGANIC CHEMISTRY: ALKANES AND HALOGENATEDHYDROCARBONS 160 UNSATURATED AND AROMATIC HYDROCARBONS 170 ORGANIC COMPOUNDS OF OXYGEN 180 ORGANIC ACIDS AND BASES AND SOME OF THEIR DERIVATIVES 190 CARBOHYDRATES 120 LIPIDS 130 AMINO ACIDS, PROTEINS, AND ENZYMES 140 NUCLEIC ACIDS 150 ENERGY METABOLISM 160 APPENDIX: PERIODIC TABLE OF THE ELEMENTS 170
  • 5. 5 | P a g e CHAPTER 1: CHEMISTRY, MATTER, AND MEASUREMENT ANDELECTRON STRUCTURE OF ATOMS In April 2003, the US Pharmacopeia, a national organization that establishes quality standards for medications, reported a case in which a physician ordered ―morphine [a powerful painkiller] 2–3 mg IV [intravenously] every 2–3 hours for pain.‖ A nurse misread the dose as ―23 mg‖ and thus administered approximately 10 times the proper amount to an 8-year-old boy with a broken leg. The boy stopped breathing but was successfully resuscitated and left the hospital three days later.Quantities and measurements are as important in our everyday lives as they are in medicine. The posted speed limits on roads and highways, such as 55 miles per hour (mph), are quantities we might encounter all the time. Both parts of a quantity, the amount (55) and the unit (mph), must be properly communicated to prevent potential problems. In chemistry, as in any technical endeavor, the proper expression of quantities is a necessary fundamental skill. As we begin our journey into chemistry, we will learn this skill so that errors—from homework mistakes to traffic tickets to more serious consequences—can be avoided.The study of chemistry will open your eyes to a fascinating world. Chemical processes are continuously at work all around us. They happen as you cook and eat food, strike a match, shampoo your hair, and even read this page. Chemistry is called the central science because knowledge of chemical principles is essential for other sciences. You might be surprised at the extent to which chemistry pervades your life. What Is Chemistry: Learning Objectives Define chemistry in relation to other sciences.Identify the general steps in the scientific method.Chemistry is the study of matter—what it consists of, what its properties are, and how it changes. Being able to describe the ingredients in a cake and how they change when the cake is baked is called chemistry. Matter is anything that has mass and takes up space—that is, anything that is physically real. Some things are easily identified as matter—this book, for example. Others are not so obvious. Because we move so easily through air, we sometimes forget that it, too, is matter.Chemistry is one branch of science. Science is the process by which we learn about the natural universe by observing, testing, and then generating models that explain our observations. Because the physical universe is so vast, there are many different branches of science (). Thus, chemistry is the study of matter, biology is the study of living things, and geology is the study of rocks and the earth. Mathematics is the language of science, and we will use it to communicate some of the ideas of chemistry.Although we divide science into different fields; there is much overlap among them. For example, some biologists and chemists work in both fields so much that their work is called biochemistry. Similarly, geology and chemistry overlap in the field called geochemistry. Shows how many of the individual fields of science are related. Figure 1.1 the Relationships between Some of the Major Branches of Science
  • 6. 6 | P a g e Chemistry lies more or less in the middle, which emphasizes its importance to many branches of science.Note: There are many other fields of science, in addition to the ones (biology, medicine, etc.) listed here.Looking Closer: AlchemyAs our understanding of the universe has changed over time, so has the practice of science. Chemistry in its modern form, based on principles that we consider valid today, was developed in the 1600s and 1700s. Before that, the study of matter was known as alchemy and was practiced mainly in China, Arabia, Egypt, and Europe.Alchemy was a somewhat mystical and secretive approach to learning how to manipulate matter. Practitioners, called alchemists, thought that all matter was composed of different proportions of the four basic elements fire, water, earth, and air and believed that if you changed the relative proportions of these elements in a substance, you could change the substance. The long-standing attempts to ―transmute‖ common metals into gold represented one goal of alchemy. Alchemy’s other major goal was to synthesize the philosopher’s stone, a material that could impart long life—even immortality. Alchemists used symbols to represent substances, some of which are shown in the accompanying figure. This was not done to better communicate ideas, as chemists do today, but to maintain the secrecy of alchemical knowledge, keeping others from sharing in it. Alchemists used symbols like these to represent substances.In spite of this secrecy, in its time alchemy was respected as a serious, scholarly endeavor. Isaac Newton, the great mathematician and physicist, was also an alchemist.Example 1.Which fields of study are branches of science? Explain.sculpture, astronomy; SolutionSculpture is not considered a science because it is not a study of some aspect of the natural universe.Astronomy is the study of stars and planets, which are part of the natural universe. Astronomy is therefore a field of science.Skill-Building Exercise; which fields of study are branches of science? Politics; physiology (the study of the function of an animal’s or a plant’s body), geophysics, agriculture.How do scientists work? Generally, they follow a process called the scientific method. The scientific method is an organized procedure for learning answers to questions. To find the answer to a question (for example, ―Why do birds fly toward Earth’s equator during the cold months?‖), a scientist goes through the following steps, which are also illustrated in:Figure 1.2 the General Steps of the Scientific Method The steps may not be as clear-cut in real life as described here, but most scientific work follows this general outline.
  • 7. 7 | P a g e Propose a hypothesis. A scientist generates a testable idea, or hypothesis, to try to answer a question or explain how the natural universe works. Some people use the word theory in place of hypothesis, but the word hypothesis is the proper word in science. For scientific applications, the word theory is a general statement that describes a large set of observations and data. A theory represents the highest level of scientific understanding.Test the hypothesis. A scientist evaluates the hypothesis by devising and carrying out experiments to test it. If the hypothesis passes the test, it may be a proper answer to the question. If the hypothesis does not pass the test, it may not be a good answer.Refine the hypothesis if necessary. Depending on the results of experiments, a scientist may want to modify the hypothesis and then test it again. Sometimes the results show the original hypothesis to be completely wrong, in which case a scientist will have to devise a new hypothesis.Not all scientific investigations are simple enough to be separated into these three discrete steps. But these steps represent the general method by which scientists learn about our natural universe.Concept Review Exercises: Define science and chemistry.Name the steps of the scientific method.Answers;Science is a process by which we learn about the natural universe by observing, testing, and then generating models that explain our observations. Chemistry is the study of matter.propose a hypothesis, test the hypothesis, and refine the hypothesis if necessa.Key Takeaways.Chemistry is the study of matter and how it behaves.The scientific method is the general process by which we learn about the natural universe.Exercises:Based on what you know, which fields are branches of science?;meteorology (the study of weather);astrophysics (the physics of planets and stars);economics (the study of money and monetary systems);astrology (the prediction of human events based on planetary and star positions);political science (the study of politics);Based on what you know, which fields are a branches of science?;history (the study of past events);ornithology (the study of birds);paleontology (the study of fossils);zoology (the study of animals);phrenology (using the shape of the head to determine personal characteristics).Which of the following are examples of matter?a baby an idea,the Empire State Building an emotion the air.Alpha Centauri, the closest known star (excluding the sun) to our solar system.Which of the following are examples of matter?;your textbook,brain cells,love,a can of soda,breakfast cereal,Suggest a name for the science that studies the physics of rocks and the earth.Suggest a name for the study of the physics of living organisms.Engineering is the practical application of scientific principles and discoveries to develop things that make our lives easier. Is medicine science or engineering? Justify your answer.Based on the definition of engineering in Exercise 7, would building a bridge over a river or road be considered science or engineering? Justify your answer.When someone says, ―I have a theory that excess salt causes high blood pressure,‖ does that person really have a theory? If it is not a theory, what is it? When a person says, ―My hypothesis is that excess calcium in the diet causes kidney stones,‖ what does the person need to do to determine if the hypothesis is correct.Some people argue that many scientists accept many scientific principles on faith. Using what you know about the scientific method, how might you argue against that assertion?.Most students take multiple English classes in school. Does the study of English use the scientific method?Answers;science;science;not science;not science;not science;matter;not matter;matter;not matter;matter;matter and geophysics.Medicine is probably closer to a field of engineering than a field of science, but this may be arguable. Ask your doctor.In scientific terms, this person has a hypothesis.Science is based on reproducible facts, not blind belief. THE CLASSIFICATION OF MATTER LEARNING OBJECTIVES;Use physical and chemical properties, including phase, to describe matter.Identify a sample of matter as an element, a compound, or a mixture.Part of understanding matter is being able to describe it. One way chemists describe matter is to assign different kinds of properties to different categories. Physical and Chemical Properties:The properties that chemists use to describe matter fall into two general categories. Physical properties are characteristics that describe matter. They include characteristics such as size, shape, color, and mass. Chemical properties are characteristics that describe how matter changes its chemical structure or composition. An example of a chemical property is flammability—a material’s ability to burn—because burning (also known as combustion) changes the chemical composition of a material.Elements and Compounds:Any sample of matter that has the same physical and chemical properties throughout the sample is called a substance. There are two types of substances. A substance that cannot be broken down into chemically simpler components is an element. Aluminum, which is used in soda cans, is an element. A substance that can be broken down into chemically simpler components (because it has more than one element) is a compound (). Water is a compound composed of the elements hydrogen and oxygen. Today, there are about 118 elements in the known universe. In contrast, scientists have identified tens of millions of different compounds to date. Note:Sometimes the word pure is added to substance, but this is not absolutely necessary. By definition, any single substance is pure.The smallest part of an element that maintains the identity of that element is called an atom. Atoms are extremely tiny; to make a line 1 inch long, you would need 217 million iron atoms. The smallest part of a compound that maintains the identity of that compound is called a molecule. Molecules are composed of atoms that are attached together and behave as a unit. Scientists usually work with millions and millions of atoms and molecules at a time. When a scientist is working with large numbers of atoms or molecules at a time, the scientist is studying the macroscopic view of the universe. However, scientists can also describe chemical events on the level of individual atoms or molecules, which is referred to as the microscopic viewpoint. We will see examples of both macroscopic and microscopic viewpoints throughout this book ().Figure 1.3 How Many Particles Are Needed for a Period in a Sentence?
  • 8. 8 | P a g e Although we do not notice it from a macroscopic perspective, matter is composed of microscopic particles so tiny that billions of them are needed to make a speck we can see with the naked eye. The ×25 and ×400,000,000 indicate the number of times the image is magnified.Mixtures:A material composed of two or more substances is a mixture. In a mixture, the individual substances maintain their chemical identities. Many mixtures are obvious combinations of two or more substances, such as a mixture of sand and water. Such mixtures are called heterogeneous mixtures. In some mixtures, the components are so intimately combined that they act like a single substance (even though they are not). Mixtures with a consistent composition throughout are called homogeneous mixtures (or solutions). Sugar dissolved in water is an example of a solution. A metal alloy, such as steel, is an example of a solid solution. Air, a mixture of mainly nitrogen and oxygen, is a gaseous solution.Example 2; How would a chemist categorize each example of matter? Saltwater, soil, water, oxygen.Solution: Saltwater acts as if it were a single substance even though it contains two substances—salt and water. Saltwater is a homogeneous mixture, or a solution.Soil is composed of small pieces of a variety of materials, so it is a heterogeneous mixture.Water is a substance; more specifically, because water is composed of hydrogen and oxygen, it is a compound.Oxygen, a substance, is an element.Skill-Building Exercise;How would a chemist categorize each example of matter?;coffee,hydrogen,an egg. Phases:Another way to classify matter is to describe it as a solid, a liquid, or a gas, which was done in the examples of solutions. These three descriptions, each implying that the matter has certain physical properties, represent the three phases of matter. A solid has a definite shape and a definite volume. Liquids ordinarily have a definite volume but not a definite shape; they take the shape of their containers. Gases have neither a definite shape nor a definite volume, and they expand to fill their containers. We encounter matter in each phase every day; in fact, we regularly encounter water in all three phases: ice (solid), water (liquid), and steam (gas).We know from our experience with water that substances can change from one phase to another if the conditions are right. Typically, varying the temperature of a substance (and, less commonly, the pressure exerted on it) can cause a phase change, a physical process in which a substance goes from one phase to another (). Phase changes have particular names depending on what phases are involved, as summarized in .Table 1.1 Phase Changes Change Name solid to liquid melting, fusion solid to gas sublimation liquid to gas boiling, evaporation liquid to solid solidification, freezing gas to liquid condensation gas to solid deposition Figure 1.4 Boiling Water
  • 9. 9 | P a g e When liquid water boils to make gaseous water, it undergoes a phase change.illustrates the relationships between the different ways matter can be classified. Figure 1.5 the Classification of Matter Matter can be classified in a variety of ways, depending on its properties.Concept Review Exercises:Explain the differences between the physical properties of matter and the chemical properties of matter.What is the difference between a heterogeneous mixture and a homogeneous mixture? Give an example of each.Give at least two examples of a phase change and state the phases involved in each.Answers:Physical properties describe the existence of matter, and chemical properties describe how substances change into other substances.A heterogeneous mixture is obviously a mixture, such as dirt; a homogeneous mixture behaves like a single substance, such as saltwater.solid to liquid (melting) and liquid to gas (boiling) (answers will vary);Key Takeaways.Matter can be described with both physical properties and chemical properties.Matter can be identified as an element, a compound, or a mixture.Exercises:Does each statement refer to a chemical property or a physical property?.Balsa is a very light wood.If held in a flame, magnesium metal burns in air.Mercury has a density of 13.6 g/mL.Human blood is red.Does each statement refer to a chemical property or a physical property?The elements sodium and chlorine can combine to make table salt.The metal tungsten does not melt until its temperature exceeds 3,000°C.The ingestion of ethyl alcohol can lead to disorientation and confusion.The boiling point of isopropyl alcohol, which is used to sterilize cuts and scrapes, is lower than the boiling point of water.Define element. How does it differ from a compound?.Define compound. How does it differ from an element?;Give two examples of a heterogeneous mixture.Give two examples of a homogeneous mixture.Identify each substance as an element, a compound, a heterogeneous mixture, or a solution.xenon, a substance that cannot be broken down into chemically simpler components.blood, a substance composed of several types of cells suspended in a salty solution called plasma.water, a substance composed of hydrogen and oxygen.Identify each substance as an element, a compound, a heterogeneous mixture, or a solution.sugar, a substance composed of carbon, hydrogen, and oxygen.hydrogen, the simplest chemical substance.dirt, a combination of rocks and decaying plant matter.Identify each substance as an element, a compound, a heterogeneous mixture, or a solution.air, primarily a mixture of nitrogen and oxygen.ringer’s lactate, a standard fluid used in medicine that contains salt, potassium, and lactate compounds all dissolved in sterile water.tartaric acid, a substance composed of carbon, hydrogen, and oxygen.Identify each material as an element, a compound, a heterogeneous mixture, or a solution.equal portions of salt and sand placed in a beaker and shaken up.a combination of beeswax dissolved in liquid hexane.hydrogen peroxide, a substance composed of hydrogen and oxygen.What word describes each phase change?solid to liquid,liquid to gas,solid to gas.What word describes each phase change?;liquid to solid,gas to liquid,gas to solid.Answers;physical property,chemical property,physical property,physical property.An element is a substance that cannot be broken down into chemically simpler components. Compounds can be broken down into simpler substances.a salt and pepper mix and a bowl of cereal (answers will vary);element,heterogeneous mixture,compound;solution;solution,compound,melting or fusion,boiling or evaporation and sublimation1.3 Measurements:Learning Objective
  • 10. 10 | P a g e Express quantities properly, using a number and a unit.A coffee maker’s instructions tell you to fill the coffeepot with 4 cups of water and use 3 scoops of coffee. When you follow these instructions, you are measuring. When you visit a doctor’s office, a nurse checks your temperature, height, weight, and perhaps blood pressure (). The nurse is also measuring.Figure 1.6 Measuring Blood Pressure A nurse or a doctor measuring a patient’s blood pressure is taking a measurement.Chemists measure the properties of matter and express these measurements as quantities. A quantity is an amount of something and consists of a number and a unit. The number tells us how many (or how much), and the unit tells us what the scale of measurement is. For example, when a distance is reported as ―5 kilometers,‖ we know that the quantity has been expressed in units of kilometers and that the number of kilometers is 5. If you ask a friend how far he or she walks from home to school and the friend answers ―12 without specifying a unit, you do not know whether your friend walks—for example, 12 miles, 12 kilometers, 12 furlongs, or 12 yards. Both a number and a unit must be included to express a quantity properly.To understand chemistry, we need a clear understanding of the units chemists work with and the rules they follow for expressing numbers. The next two sections examine the rules for expressing numbers.Example 3;Identify the number and the unit in each quantity.;one dozen eggs,2.54 centimeters,a box of pencils,88 meters per second.Solution;The number is one, and the unit is dozen eggs.The number is 2.54, and the unit is centimeter.The number 1 is implied because the quantity is only a box. The unit is box of pencils. The number is 88, and the unit is meters per second. Note that in this case the unit is actually a combination of two units: meters and seconds.Skill-Building Exercise;Identify the number and the unit in each quantity.99 bottles of soda,60 miles per hour,32 fluid ounces,98.6 degrees Fahrenheit;Concept Review Exercise,What are the two necessary parts of a quantity?Answer The two necessary parts are the number and the unit.To Your Health: Dosages.As we saw in the chapter-opening essay, a medicine can be more harmful than helpful if it is not taken in the proper dosage. A dosage (or dose) is the specific amount of a medicine that is known to be therapeutic for an ailment in a patient of a certain size. Dosages of the active ingredient in medications are usually described by units of mass, typically grams or milligrams, and generally are equated with a number of capsules or teaspoonfuls to be swallowed or injected. (For more information about mass, see .) The amount of the active ingredient in a medicine is carefully controlled so that the proper number of pills or spoonfuls contains the proper dose.Most drugs must be taken in just the right amount. If too little is taken, the desired effects will not occur (or will not occur fast enough for comfort); if too much is taken, there may be potential side effects that are worse than the original ailment. Some drugs are available in multiple dosages. For example, tablets of the medication levothyroxine sodium, a synthetic thyroid hormone for those suffering from decreased thyroid gland function, are available in 11 different doses, ranging from 25 micrograms (µg) to 300 µg. It is a doctor’s responsibility to prescribe the correct dosage for a patient, and it is a pharmacist’s responsibility to provide the patient with the correct medicine at the dosage prescribed. Thus, proper quantities—which are expressed using numbers and their associated units— are crucial for keeping us healthy. Key Takeaway Identify a quantity properly with a number and a unit. Exercises Why are both parts of a quantity important when describing it? Why are measurements an important part of any branch of science, such as chemistry? You ask a classmate how much homework your chemistry professor assigned. Your classmate answers, ―twenty.‖ Is that a proper answer? Why or why not? Identify the number and the unit in each quantity.
  • 11. 11 | P a g e five grandchildren 16 candles four score and seven years 40 days and 40 nights 12.01 grams 9.8 meters per second squared 55 miles per hour 98.6 degrees Fahrenheit Answers The number states how much, and the unit states of what. Without the number and the unit, a quantity cannot be properly communicated. No, it is not a proper answer; you do not know whether the professor meant homework problem number 20 or 20 homework problem LEARNING OBJECTIVES: Electromagnetic Radiation is energy and light. We will learn how to use it to explore atomic structure.Bohr’s Theory of atomic structure is the beginning of quantum theory and describes electrons as residing in very particular "quantized" energy levels within the atom.Shells, Sub-shells and Orbital’s are the backbone of the organizational structure of electrons in the atomElectron Configurations use shells, sub-shells and orbital to describe the relative electronic organization within the atom.Periodicity;Of electron configurations relate to periodicity of physical and chemical properties.Of valence shell configurations relate directly to relative reactivity.We know that an element is defined by the number of protons it contains. Now we will learn how electrons and their particular arrangement within an atom can affect how that atom reacts, chemically and physically. ELECTROMAGNETIC RADIATION: What is it, why is it important to our discussion about atoms and the arrangement of their electrons? .Electromagnetic radiation is energy – we describe it as a wave – visible light is only a small portion of the electromagnetic spectrum. Each type of energy (x-rays, gamma-rays, microwaves, radio waves) as well as each type of light (red, blue, green) has different wave characteristics. The characteristics which distinguish different types of light are the electromagnetic radiations;wavelength ,frequency andEnergy.
  • 12. 12 | P a g e Wavelength; the distance between two peaks (or two troughs) of the wave.Frequency; the number of wavelengths passing a given point in one second.The longer the wavelength, the more time it takes for a full wave to pass a given point (or the fewer waves pass the point in a given time). Since frequency is wavelengths per second, as the wavelength becomes longer the frequency decreases, and vice versa.Energy ; is directly proportional to the frequency-- if the frequency increases, so does the energy of the radiation and vice [12] versa. When atoms are excited by energy (such as heat) – they emit energy in the form of light (sometimes colored light) and different atoms emit different energies.What causes the emission of light? Electron transitions from higher to lower energy levels, which we will learn about when we discuss the structure of the atom. Why do different atoms emit different light? .Each atom is unique and contains its own unique electron structure in which the energies of the levels mentioned above differ.How does the emission of light relate to electron structure?.Since each atom has a unique electron structure with differing levels of energy, the energy of the transitions between those levels will also be unique.These energy spectra are how scientists explore the universe today- -to learn the content of stars, whether the universe is expanding, etc. Bohr’s Theory: When white light is passed through a prism, it is separated into its components of the spectrum, or the "rainbow" of colors. What, then, is white light made of? This "rainbow" is called a continuous spectrum, as shown below (look familiar?): When atoms are excited they emit light--but not as a continuous spectrum. The light is emitted as a specific pattern of visible, colored lines which is particular to each element. Hence these line spectra can be used to identify individual elements. The hydrogen line spectrum is shown below: Why do elements not emit continuous spectra and why does each element emit a particular set of lines which make up its line spectrum?.The answer lies in Bohr's Theory of the Atom and its structure. Bohr found that:electrons move in particular 'orbits' within the atom--meaning electrons have particular places or levels within the atom,electrons have certain allowed energy values,the closer the electron is to the nucleus, the lower the energy (the more negative the value or the value is toward the bottom of the number scale . . . -4, -3, -2, -1, 0, 1, 2, 3, 4, . . . .),
  • 13. 13 | P a g e when electrons are excited, they gain (or absorb) energy and move to a higher level (farther away from the nucleus),when electrons give off light, they emit energy and move to a lower level (closer to the nucleus),Following are two graphics which show this effect: When electrons are excited they absorb energy and move to a higher energy level (gold arrow). When they emit light, they move to a lower energy level. Violet light (violet arrow) is produced when electrons move from level 6 to level 2. Blue light (blue arrow) is produced when electrons move from level 5 to level 2. Green light (green arrow) is produced when electrons move from level 4 to level 2. Red light (red arrow) is produced when electrons move from level 3 to level 2. This series of lines which is the visible hydrogen line spectrum is called the Balmer series. The energies of these emissions just happen to be in the visible range so we can see the colors. There are many other transitions which occur, but since they are not in the visible range we cannot see them. Some have wavelengths less than 400 nm and some have wavelengths greater than 750 nm (remember, the visible range is very limited, only 400-750 nm). SHELLS, SUBSHELLS, ORBITALS:Visualize the atom as an onion with different levels of structure and sub-structure, all of which make up electron energy levels – each major energy level is designated by a number (called the quantum number): Major Shell :The major shell is the major layer of the onion--the large, thick peels which make you cry when you chop them. The major shells are designated by numbers which have integral values of 1, 2, 3, etc.These numbers are designated as the major shell quantum numbers, n.n = 1 designates the first major shell, the one closest to the nucleus and the one with the lowest (most negative) energy; n = 2 designates the second major shell, a little further from the nucleus;n = 3 designates the third major shell, etc. The major shell is the primary influence on the energy of the electron.The electron "assumes" the energy of the major shell in which it resides.The closer the (negative) electron is to the (positive) nucleus, the stronger the attraction will be, and the harder the electron is to remove. So an electron in shell n=1 will be very hard to remove while an electron in shell n=4 would be much easier to remove.Major shells contain sub shells which are a substructure within the major shell. The number of the sub shells is the same as the quantum number of the major shell, For example, major shell n = 1 has one sub shell (specifically, an 's' sub shell); n = 2 has two sub shells (an 's' and a 'p' sub shell), n = 3 has three sub shells (s, p, and d sub shells), and n = 4 has four sub shells (s, p, d and f).Sub shell :The sub shells are a substructure within the major shells--imagine each onion skin or peel containing another set of peels within each major peel.The subshells are designated by letters s, p, d, f (these letters are terms which originated from the field of spectroscopy). s, p, d, and f are different types of subshells which have different properties which we will learn about soon. These subshells contain a further substructure, which are sets of orbitals which have the same energy.OrbitalsEach subshell is further structured into orbitals. s subshells have one orbital,p subshells have three, equal energy orbitals,d subshells have five, equal energy orbitals and f subshells have seven, equal energy orbitals;each orbital can accommodate a maximum of two electrons, and;each orbital takes on the characteristics of its subshell and major shell.s subshell orbitals (there is only one per major shell) are spherical,p subshell orbitals (there are three of them per major shell) are dumbell shaped and directed along the x, y and z axis,d subshell orbitals (there are five of them per major shell) have a different shape [I only want you to recognize s and p shapes].Below is shown the relative energy levels and structure of the hydrogen atom. Remember, n = 1 is the major shell closest to the nucleus and it has only one subshell which, in turn, contains only one orbital, which can contain two electrons. What is the maximum number of electrons that can reside in the first major shell? In the diagram, the major shells are designated by the black lines coming from the energy arrow. The different types of subshells are indicated by the differently colored boxes. The orbitals themselves are the individual boxes. Remember, each box (orbital) can contain only a maximum of two electrons. Consequently, the energy of an electron is going to depend upon "which box it is sitting in" and what the energy of that box is. The lower the box (the closer it is to the nucleus) the lower (more negative) the energy and the more tightly an electron in that box is held.
  • 14. 14 | P a g e Although the major shell primarily determines the energy of an electron, there are minor differences between the energies of the subshells within any major shell, particularly in an atom with more than one electron (actually, any atom other than hydrogen):s subshells are the lowest energy subshell within a shell,p subshells are next lowest,d subshells are higher than p subshells and f subshells are higher than d subshells Once we have many electrons (which means many shells and subshells) in an atom, we begin to see some overlap of subshells--particularly, the s subshell from the fourth level (4s) overlaps with the d subshell from the third level (3d) such as shown below: Shapes of the subshells:For many reasons, we cannot define exactly where an electron is within an atom. We must, instead, define the volume which will most likely contain electron density. Consequently, the shapes of those volumes which can contain electron density are somewhat "fuzzy". We can depict volumes of high electron density (many dots) or volumes of low electron density (few dots), as shown in the diagrams below. s subshell orbitals are always spherical--like beach balls,p subshell orbitals are dumbbell shaped;all three p orbitals within any p subshell are the same except for their orientation on the x,y,z axes,d subshell orbitals have different shapes, as do f subshell orbitals. I have included a diagram of the d subshell orbitals for your information, but I only want you to know the shapes of the s and p subshell orbitals Cross-sections of an s-subshell orbital
  • 15. 15 | P a g e A spherical s subshell orbital with high (very blue) and decreasing (less blue) electron density All s subshell orbitals are spherical, the main difference; between different major shells is in the size of the sphere Electron density model p subshell orbitals d subshell orbitals:Electron Configurations are a particular arrangement or distribution of electrons among different subshells and shells within an atom. Pattern:1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10 5p6 6s2 5d10 6p6 ;lower energy higher energy ;strongest held e- less tightly held e- ;You can see this pattern emerging from the energy levels in the diagrams above.Symbols:the letters refer to the type of subshell s, p, d or f;the coefficients (numbers) to the left of each letter represent which major shell 1, 2, 3, etc.the subscript numbers represent the number of electrons present in the subshell.Pauli Exclusion Principle: an orbital can contain no more than two electrons and those two electrons must be paired, in other words, they must have opposite spin (usually indicated by one up-arrow and one down-arrow, as we will see shortly).Hund’s Rule: in a subshell where there are multiple orbitals with the same energy, electrons will enter the each orbital singly until all orbitals are half filled before pairing with other electrons in the subshell.Orbital Diagrams: For ground state electron configurations, electrons enter the electron configuration (orbital diagram) pattern beginning at the lowest energy and filling the pattern to the highest energy while obeying the Pauli Exclusion Principle and Hund’s Rule.Examples: Orbital Diagrams or Electron Configurations for: H, He Row 1.Orbital Diagrams or Electron Configurations for: Li, Be, B, N, F, Ne Row 2:
  • 16. 16 | P a g e Below are shown electronic configurations for the above elements in three forms of symbolism: I Complete Electron Configuration II Shorthand Electron Configuration III Shorthand Valence Electron Configuration I II III Periodic Table Row 1: 1H 1H 1s1 1H 1s1 1s 2He  2He 1s2 2He 1s2 1s Periodic Table Row 2: 3Li  3Li 1s2 2s1 3Li [He] 2s1 1s 2s 4Be   4Be 1s2 2s2 4Be [He] 2s2 1s 2s 5B   5B 1s2 2s2 2p1 5B [He] 2s2 2p1 1s 2s 2p 6C  6C 1s2 2s2 2p2 6C [He] 2s2 2p2 1s 2s 2p 7N 7N 1s2 2s2 2p3 7N [He] 2s2 2p3 1s 2s 2p 8O   8O 1s2 2s2 2p4 8O [He] 2s2 2p4 1s 2s 2p 9F    9F 1s2 2s2 2p5 9F [He] 2s2 2p5 1s 2s 2p
  • 17. 17 | P a g e 10Ne    10Ne 1s2 2s2 2p6 10Ne [He] 2s2 2p6 1s 2s 2p Please Notice:When filling a set of orbitals in the same subshell which have equivalent energies (such as the p subshell orbitals in nitrogen), each electron occupies a different orbital until the set of three orbitals is half-filled, then, and only then, do the electrons occupy the orbitals doubly and then only in the paired state (one arrow up, the other arrow down).The complete electron configuration pattern (I) shows all electrons in the atom as arrows entered into the appropriate orbitals, in the appropriate state (up or down).The shorthand electron configuration pattern (II) shows the number of all electrons in the atom as grouped superscripts of each subshell--it does not show the relative position or structure of electrons within a subshell.Please notice the blue letters in (II), they are the inner core electrons which have the same configuration for all elements in the second row (and also happen to be the same configuration of the previous noble gas, He) .The valence electrons are very special--they are the electrons in the outer most major shell. It is these electrons, and their structure, which primarily determine the chemical reactivity of atoms, as we shall soon see.Notice that in the valence electron configuration patterns (III) of row 2 elements, the inner core electrons (in blue) are represented by the noble gas element at the end of row 1, which has the exact same configuration of electrons as those of the inner core.For row 3 elements, the inner core electrons are represented by the noble gas element at the end of row 2, as you shall see--read further!Periodic Table Row 3: 11Na    11Na 1s2 2s2 2p6 3s1 11Na [Ne] 3s1 1s 2s 2p 3s 12Mg   12Mg 1s2 2s2 2p6 3s2 12Mg [Ne] 3s2 1s 2s 2p 3s 13Al   13Al 1s2 2s2 2p6 3s2 3p1 13Al [Ne] 3s2 3p1 1s 2s 2p 3s 3p 14Si     14Si 1s2 2s2 2p6 3s2 3p2 14Si [Ne] 3s2 3p2 1s 2s 2p 3s 3p 15P    15P 1s2 2s2 2p6 3s2 3p3 15P [Ne] 3s2 3p3 1s 2s 2p 3s 3p 16S    16S 1s2 2s2 2p6 3s2 3p4 16S [Ne] 3s2 3p4 1s 2s 2p 3s 3p 17Cl    17Cl 1s2 2s2 2p6 3s2 3p5 17Cl [Ne] 3s2 3p5 1s 2s 2p 3s 3p 18Ar   18Ar 1s2 2s2 2p6 3s2 3p6 18Ar [Ne] 3s2 3p6 1s 2s 2p 3s 3p Once again, please notice that the configurations in blue are the inner or core electrons (represented by the noble gas element of that configuration, Ne for row 3 elements) and the configurations in pink are the valence electrons. The electron configurations of the valence electrons are very important.Now, let's compare the electron configurations (complete and valence) of elements in a group, say, group IA:
  • 18. 18 | P a g e 3Li 3Li [He] 2s1 1s 2s 11Na   11Na [Ne] 3s1 1s 2s 2p 3s 19K     19K [Ar] 4s1 1s 2s 2p 3s 3p 4s Well, I think you can see the pattern. Within a group, elements have very similar valence electron configurations--same number of electrons in the same type of subshells but the only difference is in the major shell. What other similarities do elements in the same group exhibit? (see chapter four on the periodic table).PERIODICITY:Notice that in the orbital diagrams above the outer electrons of elements in the same group are similar: the same number of electrons, in the same types of orbitals but in different major shells.This type of periodicity can be used to quickly determine the electron configuration or orbital diagram of any element based upon its position in the periodic table.Valence Electrons and Valence Shells:the most important electrons in an atom are those on the outer-most edge of the atom (the outer major shell) – they come into contact with other atoms first and participate fully in reactions – they are the valence electrons .valence shells contain the valence electrons. Examples:10Ne 1s2 2s2 2p6 valence shell containing the maximum number of electrons ,11Na 1s2 2s2 2p6 3s1 valence shell containing one valence electron ,13Al 1s2 2s2 2p6 3s2 3p1 valence shell containing three valence electrons Note:s-block Group IA and IIA valence electrons are in the ns subshell where 'n' denotes the major shell or row p-block Group IIIA - VIIIA valence electrons are in the ns and np subshell where 'n' denotes the major shell or row d-block Group IB - VIIIB (Transition Metals) valence electrons are in the ns and (n-1)d subshell f-block Inner Transition Metals sometimes called the lanthanides & the actinides valence electrons are in the ns and (n-2)d subshell PERIODIC PROPERTIES:Many physical properties depend upon the electronic properties of the atoms. Since the valence electronic structures are periodic, those physical properties also reflect that periodicity. Properties such as atomic and ionic radii and ionization energy are periodic and can be predicted based upon an atoms relative position in the periodic table.Atomic Size:atoms increase in size as the number of shells increase—in other words, as the valence electrons occupy larger shells;the atoms become larger going down a groupatoms decrease in size as electrons are added to the same shell—in other words, the atoms become smaller across the periodic table from left to right, due to the contraction effect.As more electrons and protons are added to the same shell (as you move from atoms on the left to atoms on the right), the attraction between positive and negative increases and the size of the shell is contracted.Ionic Size:positive ions are smaller than the atoms from which they are derived.the greater the size of the positive charge, the smaller size of the ion relative to the atom.negative ions are larger than the atoms from which they are derived.the greater the size of the negative charge, the larger the size of the ion relative to the atom;a series of isoelectronic ions (different ions with the same number of electrons) such as those below, are not the same size
  • 19. 19 | P a g e Ionization Energy:ionization energy is the energy required to remove an electron in the formation of an ion—the more difficult it is to remove an electron, the greater the ionization energy.smaller atoms have greater ionization energy since the valence electrons are closer to the nucleus and more strongly attracted and, therefore, more difficult to remove;ionization energy increases going up a group and across a row in the periodic table. CHAPTER 2 :ELEMENTS AND ATOMS: MENDELEEV’S FIRST PERIODIC TABLE Dmitrii Mendeleev (1834-1907; in Chemical Achievers at the Chemical Heritage Foundation) was born in Tobolsk, in Western Siberia. His chief contribution to chemistry was the establishment of the periodic system of elements. Mendeleev was one of a number of independent discoverers of the periodic law in the 1860s--that number ranging from one [Leicester 1948] to six [van Spronsen 1969] depending on the criteria one adopts. Mendeleev's formulation was clearly superior in several respects to the work of contemporary classifiers: it was the clearest, most consistent, and most systematic formulation, and Mendeleev made several testable predictions based on it. It was not, however, free from error. Scientists, even great scientists, trying to see further than others have in the past, do not always see the whole picture clearly. As noted below, Mendeleev himself corrected some of the errors within a few years; others persisted well into the 20th century.This table and the accompanying observations were first presented to the Russian Chemical Society in March 1869. (Actually, Mendeleev was ill, and his colleague Nikolai Menshutkin presented his paper [Menschutkin 1934].) The paper was published in the first volume of the new society's journal. That same year, a German abstract of the paper, consisting of the table and eight comments, was published in Zeitschrift für Chemie. The German abstract was the vehicle by which Mendeleev's ideas reached chemists working in Western Europe. An English translation of that German abstract is presented here. View a On the Relationship of the Properties of the Elements to their Atomic Weights.D. Mendelejeff, Zeitschrift für Chemie 12, 405-406 (1869); translation by Carmen Giunta.By ordering the elements according to increasing atomic weight in vertical rows so that the horizontal rows contain analogous elements,[1] still ordered by increasing atomic weight, one obtains the following arrangement, from which a few general conclusions may be derived
  • 20. 20 | P a g e H=1[5] Be=9,4 Mg=24 B=11 Al=27 C=12 Si=28 N=14 P=31 Li=7 The elements, if arranged according to their atomic wei
  • 21. 21 | P a g e , exhibit an evident stepwise variation [12] of properties. Chemically analogous elements have either similar atomic weights [13] (Pt, Ir, Os), or weights which increase by equal increments (K, Rb, Cs).[14] The arrangement according to atomic weight corresponds to the valence [15] of the element and to a certain extent the difference in chemical behavior, for example Li, Be, B, C, N, O, F. The elements distributed most widely in nature have small atomic weights [16], and all such elements are marked by the distinctness of their behavior. They are, therefore, the representative elements; and so the lightest element H is rightly chosen as the most representative. The magnitude of the atomic weight determines the properties of the element. Therefore, in the study of compounds, not only the quantities and properties of the elements and their reciprocal behavior are to be taken into consideration, but also the atomic weight of the elements. Thus the compounds of S and Tl [sic--Te was intended], Cl and J, display not only analogies, but also striking differences.[17] One can predict the discovery of many new elements, for example analogues of Si and Al with atomic weights of 65-75.[18] .A few atomic weights will probably require correction; for example Te cannot have the atomic weight 128, but rather 123-126.[19] .From the above table, some new analogies between elements are revealed. Thus Bo (?) [Sic--apparently Ur was intended] appears as an analogue of Bo and Al, as is well known to have been long established experimentally. (Russian Chemical Society 1, 60); Notes: [1] the principle of periodicity is apparent in this first sentence: repetition of chemical properties in a series of elements arranged by atomic weight. Note also the cosmetic difference between Mendeleev's layout and that of modern tables, which order the elements in horizontal rows such that families of elements appear in vertical columns. Mendeleev would use the latter sort of layout before long [Mendeleev 1871]. [2]This table contains several implicit predictions of unknown elements. Mendeleev soon retreated from this prediction of a heavier analogue of titanium and zirconium. His later tables [Mendeleev 1871] erroneously placed lanthanum in this spot. This original prediction was actually borne out in 1923 with the discovery of hafnium.[3]Rhodium (Rh) is misplaced. It belongs between ruthenium (Ru) and palladium (Pd). Technetium (Tc), the element which belongs between ruthenium and molybdenum (Mo) has no stable isotopes and was not synthesized until 1937.[4]Most of the elements in this column are slightly out of order. After tungsten (W) should come rhenium (Re), which was not yet discovered, followed by osmium (Os), iridium (Ir), platinum (Pt), gold (Au), mercury (Hg), thallium (Tl), lead (Pb), and bismuth (Bi). Bismuth, however, is placed correctly insofar as it completes the row beginning with nitrogen (N). At this time, lead was frequently miscategorized, placed among elements which form compounds with one atom of oxygen (PbO analogous to CaO, for example); however, lead also forms a compound with two atoms of oxygen (PbO2 analogous to CO2) and it belongs in the same group as carbon (C). Similarly, thallium was often placed among elements which form compounds with one atom of chlorine (TlCl analogous to NaCl, for example); however, thallium also forms a compound with three atoms of chlorine (TlCl3 analogous to BCl3) and it belongs in the same group as boron (B).[5]The classification of hydrogen has been an issue throughout the history of periodic systems. Some tables place hydrogen with the alkali metals (lithium, sodium, etc.), some with the halogens (fluorine, chlorine, etc.), some with both, and some in a box of its own detached from the main body of the table. Mendeleev's original table did none of the above, placing it in the same row as copper, silver, and mercury.[6]The prediction of an unknown analogue of aluminum was borne out by the discovery in 1875 of gallium (atomic weight = 70), the first of Mendeleev's predictions to be so confirmed. [Lecoq de Boisbaudran 1877][7]Uranium (standard symbol U) is misplaced. Its atomic weight is actually more than double the value given here. The element which belongs between cadmium (Cd) and tin (Sn) is.indium (In), and Mendeleev put indium there in the next version of his table [Mendeleev 1871]. The proper place for uranium, however, would not be found until the 1940s.[8]The prediction of an unknown analogue of silicon was borne out by the discovery in 1886 of germanium (atomic weight = 73). [Winkler 1886][9]In German publications, J is frequently used instead of I as the chemical symbol for iodine (Jod, in German). Iodine is placed correctly after tellurium (i.e., with the halogens) despite having a lower atomic weight than tellurium. See comment 7 after the table.[10]The prediction of an unknown element following calcium is a weak version of Mendeleev's subsequent prediction of the element we now know as scandium, discovered in 1879 [Nilson 1879]. In Mendeleev's 1871 table [Mendeleev 1871] the missing element is correctly placed between calcium and titanium, and as an analogue of yttrium. That the 1869 prediction is flawed can be seen from the fact that every other entry in the bottom reaches of the table is wrong. (See next note.) Still, the prediction deserves more credit than van Spronsen gave it [van Spronsen 1969, p. 220]: "That the element next to calcium later proved to be scandium was fortuitous; Mendeleev cannot be said to have already foreseen this element in 1869."
  • 22. 22 | P a g e [11]The elements placed in the last four rows of the table puzzled Mendeleev, as is apparent from the glut of question marks and the fact that several are out of order according to their assigned atomic weights. Many of these elements were rare and poorly characterized at the time. Didymium appeared in many lists of elements at this time, but it was later proved to consist of two elements, praseodymium and neodymium. The atomic weights of erbium, yttrium (standard symbol Y), indium, cerium, lanthanum, and thorium are wrong. The interdependence of atomic weights and chemical formulas that plagued determinations of atomic weight since the time of Dalton was still problematic for these elements. Most of them elements (erbium, yttrium, cerium, lanthanum, and the component elements of didymium) belong to the family of rare earths, a group whose classification would present problems for many years to come. (Thorium belongs to the group of elements immediately below most of the rare earths.) Many of the rare earths were not yet discovered, and (as already noted) the atomic weights of the known elements were not well determined. The chemical properties of the rare earths are so similar that they were difficult to distinguish and to separate. Mendeleev made some progress with these elements in the next couple of years. His 1871 table [Mendeleev 1871] has correct weights for yttrium, indium, cerium, and thorium, and correct classification for yttrium and indium.[12]Translator's note: In his 1889 Faraday lecture [Mendeleev 1889], Mendeleev used the word "periodicity" rather than the phrase "stepwise variation" in translating this sentence from his 1869 paper. "Periodicity" is certainly an appropriate term to describe the cyclic repetition in properties evident in this arrangement. It is worth noting, however, that the German words read in 1869 by Western European scientists (stufenweise Abänderung) lack the implication of repetition inherent in the term periodicity. -- CJG [13]Groups of similar elements with consecutive atomic weights are a little- emphasized part of classification systems from Mendeleev's time and before (cf. Newlands 1864) to the present.[14]The existence of a very regular progression in atomic weight among elements with similar chemical behavior had attracted the attention of chemists almost from the time they began to measure atomic weights [Döbereiner 1829]. The triad of elements Mendeleev cites here includes two (rubidium and cesium) discovered in the early 1860s. Mendeleev's table, however, goes beyond strictly regular isolated triads of elements to a systematic classification (albeit not always correct) of all known elements. [15]The valence of an element is essentially the number of bonds that element can make when it forms compounds with other elements. An atom of hydrogen, for example, can make just one bond, so its valence is one; we call it monovalent. An atom of oxygen can bond with two atoms of hydrogen, so its valence is two. Some elements, particularly heavier elements, have more than one characteristic valence. (For example, lead has valence 2 and 4; thallium has valence 1 and 3. See note 4 above.) The elements in the cited series have valences 1, 2, 3, 4, 3, 2, and 1 respectively.[16]Mendeleev is correct in this observation. The two lightest elements, hydrogen and helium (the latter as yet unknown) are the most common elements in the universe, making up the bulk of stars. Oxygen and silicon are the most common elements in the earth's crust. Iron is the heaviest element among the most abundant elements in the stars and the earth's crust.[17]Although the chemical behavior of elements in the same family is similar, it is not identical: there are differences due to the difference in atomic weight. For example, both chlorine and iodine form compounds with one atom of hydrogen: HCl and HI. These compounds are similar, in that they are both corrosive gases which dissolve readily in water. But they differ in that HI has, for example, a higher boiling point and melting point than HCl (typical of the heavier of a pair of related compounds).[18]In later publications [Mendeleev 1871] Mendeleev went into considerable detail regarding the properties of predicted elements. The success of these predictions played a part in establishing the periodic system, although apparently not the primary part. [Brush 1996] See Scerri & Worrall 2001 for a discussion of prediction and accommodation in the periodic table. [19]Mendeleev went on to incorporate this "correction" in his 1871 table [Mendeleev 1871], listing the atomic weight of tellurium as 125. But the "correction" is erroneous. Mendeleev was right to put tellurium in the same group with sulfur and oxygen; however, strict order of atomic weights according to the best information he had available would have required iodine (127) to come before tellurium (128). He was suspicious of this apparent inversion of atomic weight order; as it happens, the atomic weights Mendeleev had available to him agree with the currently accepted values.While his suggestion to change that of tellurium was wrong, his classification was correct and his faith in the regularity of the periodic system was only slightly misplaced. The natural order of the elements is not quite one of increasing atomic weight, but one of increasing atomic number. In 1913, a discovery by Henry Moseley made the atomic number more than simply a rank order for the elements [Moseley 1913, 1914]. The atomic number is the same as the quantity of positive charge in the nucleus of an atom. The periodic system contains a few "inversions" of atomic weight, but no inversions of atomic number.References: Stephen G. Brush, "The Reception of Mendeleev's Periodic Law in America and Britain," Isis 87 595-628 (1996) ;Johann Döbereiner, Poggendorf's Annalen der Physik und Chemie 15, 301-307 (1829); translated as "An Attempt to Group Elementary Substances according to Their Analogies," in Henry M. Leicester & Herbert S. Klickstein, eds., A Source Book in Chemistry, 1400-1900 (Cambridge,
  • 23. 23 | P a g e When a new entry-level textbook in chemistry comes out, the obvious first question is ―Why?‖ Why write another book when there are other texts available? .Actually, we had two main reasons. First, of all the textbooks that are available for a one- semester general chemistry, organic chemistry, and biochemistry (GOB) course, virtually all are single-author textbooks. Why this one stands out—and, we would argue, why this textbook might be preferable—is that the author team is composed of chemistry faculty who specialize in the G part, the O part, and the B part. One of us (DWB) is a physical chemist who spends a lot of time in the general chemistry sequence, whether for nonscience majors, health profession majors, or science and engineering majors. Another author (JWH) is an organic chemist by training and an experienced textbook author, while the third author (RJS) is a biochemistry professor and also a successful textbook author. All three authors are experienced, successful teachers. Thus, right from the start, this author team brings the appropriate experience and expertise that can combine to write a superior textbook for this market.The second reason was the opportunity presented by the unique publishing strategy of Flat World Knowledge. The entire author team is excited about the potential for online presentation of content in this Internet age. In addition to having the content online, print copies of the textbook are readily available, as are individual chapters, vocabulary cards, exercise solutions, and other products. The easy availability of these items maximizes the ability of students to customize their personal tools, increasing their chances for success in a one-semester chemistry course.This textbook is intended for the one-semester GOB course. Although a two-semester GOB sequence is available at many colleges and universities, one-semester GOB offerings are increasing in popularity. The need to cover so many topics in one semester or quarter places additional pressure on the tools used to teach the course, and the authors feel that a textbook developed explicitly for the one-semester course will provide students with a superior educational experience. Many one-semester GOB courses employ either a rewritten, watered-down two-semester textbook or a bona fide two-semester textbook with cherry-picked topics. In the opinion of this author team, neither choice provides students with the best learning experience. This textbook does not have a two-semester counterpart. It was developed specifically for the one-semester GOB course. As such, the chapters are short and succinct, covering the fundamental material and leaving out the extraneous. We recognize that students taking this particular course are likely interested in health professions, such as nursing, occupational therapy, physical therapy, physician assistance, and the like. As such, we have focused certain examples and textbook features on these areas so students realize from the beginning how these basic chemistry topics apply to their career choice.This textbook is divided into approximately one-half general chemistry topics, one-fourth organic chemistry topics, and one-fourth biochemistry topics. We feel that these fractions provide the appropriate mix of chemistry topics for most students’ needs. The presentation is standard: there is no attempt to integrate organic and biological chemistry throughout a general chemistry textbook, although there is an early introduction to organic chemistry so that carbon-containing compounds can be included as soon as possible. The first chapter stands out a bit for covering a relatively large amount of material, but that is necessary. There is a certain skill set that students must have to be successful in any GOB course, and rather than relegate these skills to an appendix that is too often overlooked, the first chapter covers them explicitly. Some of these topics can be omitted at the instructor’s discretion.The G part of the textbook then continues into atoms and molecules, chemical reactions, simple stoichiometry, energy, the phases of matter, solutions, and acids and bases (including a short treatment of equilibrium) and then ends with nuclear chemistry. The O part of the textbook starts with hydrocarbons and quickly covers aromatic compounds and the basic functional groups, focusing on those functional groups that have specific applications in biochemistry. The B part starts by immediately applying the organic knowledge to carbohydrates and other biologically important compounds. This section ends with a chapter on metabolism, which is, after all, the ultimate goal for a textbook like this—a discussion of the chemistry of life.Each chapter is filled with example problems that illustrate the concepts at hand. In the mathematical exercises, a consistent style of problem solving has been used. We understand that there may be more than one way to solve a mathematical problem, but having a consistent problem-solving style increases the chance for student comprehension. Particular emphasis is placed on the units of quantities and how they have to work out appropriately in algebraic treatments. For each example problem, there is a Skill-Building Exercise immediately following that will help students practice the very same concept but without an elaborate answer worked out.Every section of each chapter starts with one or more Learning Objectives that preview the section. These Learning Objectives are echoed at the end of each section with Key Takeaways as well as Concept Review Exercises that ask about the main ideas of the section. Sections then end with a set of exercises that students can use to immediately put the knowledge of that section into practice. Most of the exercises are paired, so that students can work two similar exercises for additional practice. Finally, Additional Exercises at the end of each chapter ask more challenging questions, bring multiple concepts together into a single exercise, or extend the chapter concepts to broader perspectives. The complete exercise portfolio of the textbook—Skill-Building Exercises, Concept Review Exercises, end-of-section exercises, and Additional Exercises—provides multiple opportunities for students to practice the content.
  • 24. 24 | P a g e Other features in the textbook include Looking Closer, a chance to expand on a topic more than a typical textbook would. We have selected topics that are relevant and should appeal to students at this level. There are essays titled To Your Health that focus on how some of the topics relate directly to health issues—the focus of most of the students in this course. Do students realize that the simple act of breathing, something most of us do without thinking, is a gas law in action? Most chapters also have a Career Focus that presents an occupation related to the health professions. Students at this level may not know exactly what they want to do in the health professions, so having these essays gives some information about the career possibilities awaiting them.These features are kept to a minimum, however; this is a one-semester textbook covering general chemistry, organic chemistry, and biochemistry. We recognize that users appreciate features like this, but we also recognize the need to focus on the core chemistry content. We hope we have reached an appropriate balance with the amount of additional features.We hope that this textbook meets your and your students’ goals.David W. Ball,John W. Hill and Rhonda J. Scott:February 2011 CHAPTER 21 :APPENDIX: PERIODIC TABLE OF THE ELEMENTS In this chapter, we present some data on the chemical elements. The periodic table lists all the known chemical elements, arranged by atomic number (that is, the number of protons in the nucleus). The periodic table is arguably the best tool in all of science; no other branch of science can summarize its fundamental constituents in such a concise and useful way. Many of the physical and chemical properties of the elements are either known or understood based on their positions on the periodic table. Periodic tables are available with a variety of chemical and physical properties listed in each element’s box. What follows here is a relatively simple version. The Internet is a great place to find periodic tables that contain additional information.One item on most periodic tables is the atomic mass of each element. For many applications, only one or two decimal places are necessary for the atomic mass. However, some applications (especially nuclear chemistry; see ) require more decimal places. The atomic masses in represent the number of decimal places recognized by the International Union of Pure and Applied Chemistry, the worldwide body that develops standards for chemistry. The atomic masses of some elements are known very precisely, to a large number of decimal places. The atomic masses of other elements, especially radioactive elements, are not known as precisely. Some elements, such as lithium, can have varying atomic masses depending on how their isotopes are isolated.The web offers many interactive periodic table resources. For example, see Table 21.1 the Basics of the Elements of the Periodic Table
  • 25. 25 | P a g e N a m e A t o m i c S y m b o l A t o m i c N u m b e r A t o m i c M a s s F o o t n o t e s a c t i n i u m * A c 8 9 a l u m i n u m A l 1 3 2 6 . 9 8 1 5 3 8 6 ( 8 ) a m e r i c i u m * A m 9 5 a n t i m o n y S b 5 1 1 2 1 . 7 6 0 ( 1 ) g a r g o n A r 1 8 3 9 . 9 4 8 ( 1 ) g , r a A 3 7 N a m e A t o m i c S y m b o l A t o m i c N u m b e r A t o m i c M a s s F o o t n o t e s r s n i c s 3 4 . 9 2 1 6 0 ( 2 ) a s t a t i n e * A t 8 5 b a r i u m B a 5 6 1 3 7 . 3 2 7 ( 7 ) b e r k e l i u m * B k 9 7 b e r y l l i u m B e 4 9 . 0 1 2 1 8 2 ( 3 ) b i s m B i 8 3 2 0 8 . N a m e A t o m i c S y m b o l A t o m i c N u m b e r u t h b o h r i u m * B h 1 0 7 b o r o n B 5 b r o m i n e B r 3 5 c a d m i u m C d 4 8 c a e s i u m ( c C s 5 5
  • 26. 26 | P a g e N a m e A t o m i c S y m b o l A t o m i c N u m b e r A t o m i c M a s s F o o t n o t e s e s i u m ) 9 ( 2 ) c a l c i u m C a 2 0 4 0 . 0 7 8 ( 4 ) g c a l i f o r n i u m * C f 9 8 c a r b o n C 6 1 2 . 0 1 0 7 ( 8 ) g , r c e r i u m C e 5 8 1 4 0 . 1 1 6 ( 1 ) g c h l o r i n C l 1 7 3 5 . 4 5 3 ( g , m , r N a m e A t o m i c S y m b o l A t o m i c N u m b e r A t o m i c M a s s F o o t n o t e s e 2 ) c h r o m i u m C r 2 4 5 1 . 9 9 6 1 ( 6 ) c o b a l t C o 2 7 5 8 . 9 3 3 1 9 5 ( 5 ) c o p e r n i c i u m * C n 1 1 2 c o p p e r C u 2 9 6 3 . 5 4 6 ( 3 ) r c u r i u m * C m 9 6 N a m e A t o m i c S y m b o l A t o m i c N u m b e r d a r m s t a d t i u m * D s 1 1 0 d u b n i u m * D b 1 0 5 d y s p r o s i u m D y 6 6 e i n s t e i n i u m * E s 9 9 e r b i u m E r 6 8
  • 27. 27 | P a g e N a m e A t o m i c S y m b o l A t o m i c N u m b e r A t o m i c M a s s F o o t n o t e s e u r o p i u m E u 6 3 1 5 1 . 9 6 4 ( 1 ) g f e r m i u m * F m 1 0 0 f l u o r i n e F 9 1 8 . 9 9 8 4 0 3 2 ( 5 ) f r a n c i u m * F r 8 7 g a d o l i n i u m G d 6 4 1 5 7 . 2 5 ( 3 ) g g a G a 3 1 6 9 N a m e A t o m i c S y m b o l A t o m i c N u m b e r A t o m i c M a s s F o o t n o t e s l l i u m . 7 2 3 ( 1 ) g e r m a n i u m G e 3 2 7 2 . 6 4 ( 1 ) g o l d A u 7 9 1 9 6 . 9 6 6 5 6 9 ( 4 ) h a f n i u m H f 7 2 1 7 8 . 4 9 ( 2 ) h a s s i u m * H s 1 0 8 h e l i u m H e 2 4 . 0 0 2 6 0 2 g , r N a m e A t o m i c S y m b o l A t o m i c N u m b e r h o l m i u m H o 6 7 h y d r o g e n H 1 i n d i u m I n 4 9 i o d i n e I 5 3 i r i d i u m I r 7 7
  • 28. 28 | P a g e N a m e A t o m i c S y m b o l A t o m i c N u m b e r A t o m i c M a s s F o o t n o t e s ( 3 ) i r o n F e 2 6 5 5 . 8 4 5 ( 2 ) k r y p t o n K r 3 6 8 3 . 7 9 8 ( 2 ) g , m l a n t h a n u m L a 5 7 1 3 8 . 9 0 5 4 7 ( 7 ) g l a w r e n c i u m * L r 1 0 3 l e a d P b 8 2 2 0 7 . 2 ( 1 ) g , r N a m e A t o m i c S y m b o l A t o m i c N u m b e r A t o m i c M a s s F o o t n o t e s l i t h i u m L i 3 [ 6 . 9 4 1 ( 2 ) ] † g , m , r l u t e t i u m L u 7 1 1 7 4 . 9 6 7 ( 1 ) g m a g n e s i u m M g 1 2 2 4 . 3 0 5 0 ( 6 ) m a n g a n e s e M n 2 5 5 4 . 9 3 8 0 4 5 ( 5 ) m e i t n e r i u m * M t 1 0 9 N a m e A t o m i c S y m b o l A t o m i c N u m b e r m e n d e l e v i u m * M d 1 0 1 m e r c u r y H g 8 0 m o l y b d e n u m M o 4 2 n e o d y m i u m N d 6 0 n e o n N e 1 0 n N 9
  • 29. 29 | P a g e N a m e A t o m i c S y m b o l A t o m i c N u m b e r A t o m i c M a s s F o o t n o t e s e p t u n i u m * p 3 n i c k e l N i 2 8 5 8 . 6 9 3 4 ( 2 ) n i o b i u m N b 4 1 9 2 . 9 0 6 3 8 ( 2 ) n i t r o g e n N 7 1 4 . 0 0 6 7 ( 2 ) g , r n o b e l i u m * N o 1 0 2 o s m i u O s 7 6 1 9 0 . 2 g N a m e A t o m i c S y m b o l A t o m i c N u m b e r A t o m i c M a s s F o o t n o t e s m 3 ( 3 ) o x y g e n O 8 1 5 . 9 9 9 4 ( 3 ) g , r p a l l a d i u m P d 4 6 1 0 6 . 4 2 ( 1 ) g p h o s p h o r u s P 1 5 3 0 . 9 7 3 7 6 2 ( 2 ) p l a t i n u m P t 7 8 1 9 5 . 0 8 4 ( 9 ) p l u t o n i u m P u 9 4 N a m e A t o m i c S y m b o l A t o m i c N u m b e r * p o l o n i u m * P o 8 4 p o t a s s i u m K 1 9 p r a s e o d y m i u m P r 5 9 p r o m e t h i u m * P m 6 1 p r o t a c t i n i u P a 9 1
  • 30. 30 | P a g e N a m e A t o m i c S y m b o l A t o m i c N u m b e r A t o m i c M a s s F o o t n o t e s m * ) r a d i u m * R a 8 8 r a d o n * R n 8 6 r o e n t g e n i u m * R g 1 1 1 r h e n i u m R e 7 5 1 8 6 . 2 0 7 ( 1 ) r h o d i u m R h 4 5 1 0 2 . 9 0 5 5 0 ( 2 ) r u b R b 3 7 8 5 . g N a m e A t o m i c S y m b o l A t o m i c N u m b e r A t o m i c M a s s F o o t n o t e s i d i u m 4 6 7 8 ( 3 ) r u t h e n i u m R u 4 4 1 0 1 . 0 7 ( 2 ) g r u t h e r f o r d i u m * R f 1 0 4 s a m a r i u m S m 6 2 1 5 0 . 3 6 ( 2 ) g s c a n d i u m S c 2 1 4 4 . 9 5 5 9 1 2 ( 6 ) s e a S g 1 0 6 N a m e A t o m i c S y m b o l A t o m i c N u m b e r b o r g i u m * s e l e n i u m S e 3 4 s i l i c o n S i 1 4 s i l v e r A g 4 7 s o d i u m N a 1 1 s t r S r 3 8
  • 31. 31 | P a g e N a m e A t o m i c S y m b o l A t o m i c N u m b e r A t o m i c M a s s F o o t n o t e s o n t i u m 6 2 ( 1 ) r s u l f u r S 1 6 3 2 . 0 6 5 ( 5 ) g , r t a n t a l u m T a 7 3 1 8 0 . 9 4 7 8 8 ( 2 ) t e c h n e t i u m * T c 4 3 t e l l u r i u m T e 5 2 1 2 7 . 6 0 ( 3 ) g t e r b i u m T b 6 5 1 5 8 . 9 2 5 N a m e A t o m i c S y m b o l A t o m i c N u m b e r A t o m i c M a s s F o o t n o t e s 3 5 ( 2 ) t h a l l i u m T l 8 1 2 0 4 . 3 8 3 3 ( 2 ) t h o r i u m * T h 9 0 2 3 2 . 0 3 8 0 6 ( 2 ) g t h u l i u m T m 6 9 1 6 8 . 9 3 4 2 1 ( 2 ) t i n S n 5 0 1 1 8 . 7 1 0 ( 7 ) g t i t a T i 2 2 4 7 . 8 N a m e A t o m i c S y m b o l A t o m i c N u m b e r n i u m t u n g s t e n W 7 4 u n u n h e x i u m * U u h 1 1 6 u n u n o c t i u m * U u o 1 1 8 u n u n p e n t i u m * U u p 1 1 5 u n u n q u U u q 1 1 4
  • 32. 32 | P a g e N a m e A t o m i c S y m b o l A t o m i c N u m b e r A t o m i c M a s s F o o t n o t e s a d i u m * u n u n t r i u m * U u t 1 1 3 u r a n i u m * U 9 2 2 3 8 . 0 2 8 9 1 ( 3 ) g , m v a n a d V 2 3 5 0 . 9 4 N a m e A t o m i c S y m b o l A t o m i c N u m b e r A t o m i c M a s s F o o t n o t e s i u m 1 5 ( 1 ) x e n o n X e 5 4 1 3 1 . 2 9 3 ( 6 ) g , m y t t e r b i u m Y b 7 0 1 7 3 . 0 4 ( 3 ) g y t t r i u m Y 3 9 8 8 . 9 0 5 8 5 ( N a m e A t o m i c S y m b o l A t o m i c N u m b e r z i n c Z n 3 0 z i r c o n i u m Z r 4 0
  • 33. 33 | P a g e *Element has no stable nuclides. However, three such elements (Th, Pa, and U) have a characteristic terrestrial isotopic composition, and for these an atomic mass is tabulated. Commercially available Li materials have atomic weights that range between 6.939 and 6.996; if a more accurate value is required, it must be determined for the specific material. g Geological specimens are known in which the element has an isotopic composition outside the limits for normal material. The difference between the atomic mass of the element in such specimens and that given in the table may exceed the stated uncertainty. Modified isotopic compositions may be found in commercially available material because it has been subjected to an undisclosed or inadvertent isotopic fractionation. Substantial deviations in the atomic mass of the element from that given in the table can occur. Range in isotopic composition of normal terrestrial material prevents a more precise Ar(E) being given; the tabulated Ar(E) value and uncertainty should be applicable to normal material. CHAPTER 20: ENERGY METABOLISM The discovery of the link between insulin and diabetes led to a period of intense research aimed at understanding exactly how insulin works in the body to regulate glucose levels. Hormones in general act by binding to some protein, known as the hormone’s receptor, thus initiating a series of events that lead to a desired outcome. In the early 1970s, the insulin receptor was purified, and researchers began to study what happens after insulin binds to its receptor and how those events are linked to the uptake and metabolism of glucose in cells.The insulin receptor is located in the cell membrane and consists of four polypeptide chains: two identical chains called α chains and two identical chains called β chains. The α chains, positioned on the outer surface of the membrane, consist of 735 amino acids each and contain the binding site for insulin. The β chains are integral membrane proteins, each composed of 620 amino acids. The binding of insulin to its receptor stimulates the β chains to catalyze the addition of phosphate groups to the specific side chains of tyrosine (referred to as phosphorylation) in the β chains and other cell proteins, leading to the activation of reactions that metabolize glucose. In this chapter we will look at the pathway that breaks down glucose—in response to activation by insulin—for the purpose of providing energy for the cell.Figure 20.1 Model of the Structure of the Insulin Receptor Life requires energy. Animals, for example, require heat energy to maintain body temperature, mechanical energy to move their limbs, and chemical energy to synthesize the compounds needed by their cells. Living cells remain organized and functioning properly only through a continual supply of energy. But only specific forms of energy can be used. Supplying a plant with energy by holding it in a flame will not prolong its life. On the other hand, a green plant is able to absorb radiant energy from the sun, the most abundant source of energy for life on the earth. Plants use this energy first to form glucose and then to make other carbohydrates, as well as lipids and proteins. Unlike plants, animals cannot directly use the sun’s energy to synthesize new compounds. They must eat plants or other animals to get carbohydrates, fats, and proteins and the chemical energy stored in them (). Once digested and transported to the cells, the nutrient molecules can be used in either of two ways: as building blocks for making new cell parts or repairing old ones or ―burned‖ for energy.Figure 20.2 Some Energy Transformations in Living Systems
  • 34. 34 | P a g e Plants and animals exist in a cycle; each requires products of the other.The thousands of coordinated chemical reactions that keep cells alive are referred to collectively as metabolism. In general, metabolic reactions are divided into two classes: the breaking down of molecules to obtain energy is catabolism, and the building of new molecules needed by living systems is anabolism.Note:Any chemical compound that participates in a metabolic reaction is a metabolite.Most of the energy required by animals is generated from lipids and carbohydrates. These fuels must be oxidized, or ―burned,‖ for the energy to be released. The oxidation process ultimately converts the lipid or carbohydrate to carbon dioxide (CO2) and water (H2O).Carbohydrate: C6H12O6 + 6O2 → 6CO2 + 6H2O + 670 kcal Lipid: C16H32O2 + 23O2 → 16CO2 + 16H2O + 2,385 kcal .These two equations summarize the biological combustion of a carbohydrate and a lipid by the cell through respiration. Respiration is the collective name for all metabolic processes in which gaseous oxygen is used to oxidize organic matter to carbon dioxide, water, and energy.Like the combustion of the common fuels we burn in our homes and cars (wood, coal, gasoline), respiration uses oxygen from the air to break down complex organic substances to carbon dioxide and water. But the energy released in the burning of wood is manifested entirely in the form of heat, and excess heat energy is not only useless but also injurious to the living cell. Living organisms instead conserve much of the energy respiration releases by channeling it into a series of stepwise reactions that produce adenosine triphosphate (ATP) or other compounds that ultimately lead to the synthesis of ATP. The remainder of the energy is released as heat and manifested as body temperature. Examines the structure of ATP and begins to explore its role as the chemical energy carrier of the body.1.5 Expressing Numbers: Significant Figures Learning Objectives:Identify the number of significant figures in a reported value.Use significant figures correctly in arithmetical operations.Scientists have established certain conventions for communicating the degree of precision of a measurement. Imagine, for example, that you are using a meterstick to measure the width of a table. The centimeters (cm) are marked off, telling you how many centimeters wide the table is. Many metersticks also have millimeters (mm) marked off, so we can measure the table to the nearest millimeter. But most metersticks do not have any finer measurements indicated, so you cannot report the table’s width any more exactly than to the nearest millimeter. All you can do is estimate the next decimal place in the measurement (). Figure 1.7 Measuring an Object to the Correct Number of Digits
  • 35. 35 | P a g e How many digits should be reported for the length of this object?.The concept of significant figures takes this limitation into account. The significant figures of a measured quantity are defined as all the digits known with certainty and the first uncertain, or estimated, digit. It makes no sense to report any digits after the first uncertain one, so it is the last digit reported in a measurement. Zeros are used when needed to place the significant figures in their correct positions. Thus, zeros may not be significant figures.Note:―Sig figs‖ is a common abbreviation for significant figures.For example, if a table is measured and reported as being 1,357 mm wide, the number 1,357 has four significant figures. The 1 (thousands), the 3 (hundreds), and the 5 (tens) are certain; the 7 (units) is assumed to have been estimated. It would make no sense to report such a measurement as 1,357.0 or 1,357.00 because that would suggest the measuring instrument was able to determine the width to the nearest tenth or hundredth of a millimeter, when in fact it shows only tens of millimeters and the units have to be estimated.On the other hand, if a measurement is reported as 150 mm, the 1 (hundreds) and the 5 (tens) are known to be significant, but how do we know whether the zero is or is not significant? The measuring instrument could have had marks indicating every 10 mm or marks indicating every 1 mm. Is the zero an estimate, or is the 5 an estimate and the zero a placeholder?.The rules for deciding which digits in a measurement are significant are as follows:All nonzero digits are significant. In 1,357, all the digits are significant.Captive (or embedded) zeros, which are zeros between significant digits, are significant. In 405, all the digits are significant.Leading zeros, which are zeros at the beginning of a decimal number less than 1, are not significant. In 0.000458, the first four digits are leading zeros and are not significant. The zeros serve only to put the digits 4, 5, and 8 in the correct positions. This number has three significant figures.Trailing zeros, which are zeros at the end of a number, are significant only if the number has a decimal point. Thus, in 1,500, the two trailing zeros are not significant because the number is written without a decimal point; the number has two significant figures. However, in 1,500.00, all six digits are significant because the number has a decimal point.Example 8;How many significant digits does each number have?;6,798,000,6,000,798,6,000,798.00,0.0006798;Solution:four (by rules 1 and 4),seven (by rules 1 and 2),nine (by rules 1, 2, and 4),four (by rules 1 and 3),Skill- Building Exercise;How many significant digits does each number have?,2.1828,0.005505,55,050,5,500 Combining Numbers:It is important to be aware of significant figures when you are mathematically manipulating numbers. For example, dividing 125 by 307 on a calculator gives 0.4071661238… to an infinite number of digits. But do the digits in this answer have any practical meaning, especially when you are starting with numbers that have only three significant figures each? When performing mathematical operations, there are two rules for limiting the number of significant figures in an answer—one rule is for addition and subtraction, and one rule is for multiplication and division.For addition or subtraction, the rule is to stack all the numbers with their decimal points aligned and then limit the answer’s significant figures to the rightmost column for which all the numbers have significant figures. Consider the following: The arrow points to the rightmost column in which all the numbers have significant figures—in this case, the tenths place. Therefore, we will limit our final answer to the tenths place. Is our final answer therefore 1,459.0? No, because when we drop digits from the end of a number, we also have to round the number. Notice that the second dropped digit, in the hundredths place, is 8. This suggests that the answer is actually closer to 1,459.1 than it is to 1,459.0, so we need to round up to 1,459.1. The rules in rounding are simple: If the first dropped digit is 5 or higher, round up. If the first dropped digit is lower than 5, do not round up. For multiplication or division, the rule is to count the number of significant figures in each number being multiplied or divided and then limit the significant figures in the answer to the lowest count. An example is as follows:
  • 36. 36 | P a g e The final answer, limited to four significant figures, is 4,094. The first digit dropped is 1, so we do not round up.Scientific notation provides a way of communicating significant figures without ambiguity. You simply include all the significant figures in the leading number. For example, the number 450 has two significant figures and would be written in scientific notation as 4.5 × 102 , whereas 450.0 has four significant figures and would be written as 4.500 × 102 . In scientific notation, all significant figures are listed explicitly.Example 9;Write the answer for each expression using scientific notation with the appropriate number of significant figures.23.096 × 90.300,125 × 9.000,1,027 + 610 + 363.06:Solution:The calculator answer is 2,085.5688, but we need to round it to five significant figures. Because the first digit to be dropped (in the hundredths place) is greater than 5, we round up to 2,085.6, which in scientific notation is 2.0856 × 103 .The calculator gives 1,125 as the answer, but we limit it to three significant figures and convert into scientific notation: 1.13 × 103 .The calculator gives 2,000.06 as the answer, but because 610 has its farthest-right significant figure in the tens column, our answer must be limited to the tens position: 2.0 × 103 .Skill-Building Exercise;Write the answer for each expression using scientific notation with the appropriate number of significant figures,217 ÷ 903,13.77 + 908.226 + 515,255.0 – 99,0.00666 × 321 Remember that calculators do not understand significant figures. You are the one who must apply the rules of significant figures to a result from your calculator.Concept Review Exercises;Explain why the concept of significant figures is important in numerical calculations.State the rules for determining the significant figures in a measurement.When do you round a number up, and when do you not round a number up?.Answers;Significant figures represent all the known digits of a measurement plus the first estimated one.All nonzero digits are significant; zeros between nonzero digits are significant; zeros at the end of a nondecimal number or the beginning of a decimal number are not significant; zeros at the end of a decimal number are significant.Round up only if the first digit dropped is 5 or higher.Key Takeaways;Significant figures properly report the number of measured and estimated digits in a measurement.There are rules for applying significant figures in calculations.Exercises;Define significant figures. Why are they important?.Define the different types of zeros found in a number and explain whether or not they are significant.How many significant figures are in each number?,140,0.009830,15,050,221,560,000,5.67 × 103 ,2.9600 × 10−5 .How many significant figures are in each number?1.05,9,500,0.0004505,0.00045050,7.210 × 106 ,5.00 × 10−6 .Round each number to three significant figures.34,705,34,750,34,570.Round each number to four significant figures.34,705,0.00541098.90443 × 108 .Perform each operation and express the answer to the correct number of significant figures.467.88 + 23.0 + 1,306 = ?.10,075 + 5,822.09 − 34.0 = ?.0.00565 + 0.002333 + 0.0991 = ?.Perform each operation and express the answer to the correct number of significant figures.0.9812 + 1.660 + 8.6502 = ?.189 + 3,201.8 − 1,100 = ?.675.0 − 24 + 1,190 = ?.Perform each operation and express the answer to the correct number of significant figures.439 × 8,767 = ?,23.09 ÷ 13.009 = ?,1.009 × 876 = ?.Perform each operation and express the answer to the correct number of significant figures.3.00 ÷ 1.9979 = ?,2,300 × 185 = ?,16.00 × 4.0 = ?.Use your calculator to solve each equation. Express each answer in proper scientific notation and with the proper number of significant figures. If you do not get the correct answers, you may not be entering scientific notation into your calculator properly, so ask your instructor for assistance. (5.6 × 103 ) × (9.04 × 10−7 ) = ? (8.331 × 10−2 ) × (2.45 × 105 ) = ? 983.09 ÷ (5.390 × 105 ) = ? 0.00432 ÷ (3.9001 × 103 ) = ? Use your calculator to solve each equation. Express each answer in proper scientific notation and with the proper number of significant figures. If you do not get the correct answers, you may not be entering scientific notation into your calculator properly, so ask your instructor for assistance. (5.2 × 106 ) × (3.33 × 10−2 ) = ? (7.108 × 103 ) × (9.994 × 10−5 ) = ? (6.022 × 107 ) ÷ (1.381 × 10−8 ) = ?
  • 37. 37 | P a g e (2.997 × 108 ) ÷ (1.58 × 1034 ) = ? Answers Significant figures represent all the known digits plus the first estimated digit of a measurement; they are the only values worth reporting in a measurement. two four four five three five 34,700 34,800 34,600 1,797 15,863 0.1071 3,850,000 1.775
  • 38. 38 | P a g e 884 5.1 × 10−3 2.04 × 104 1.824 × 10−3 1.11 × 10−6 Next 1.6 The International System of Units Learning Objective Recognize the SI base units and explain the system of prefixes used with them. Now that we have discussed some of the conventions for expressing numbers, let us focus on the other component of a quantity—the units. People who live in the United States measure weight in pounds, height in feet and inches, and a car’s speed in miles per hour. In contrast, chemistry and other branches of science use the International System of Units (also known as SI after Système Internationale d’Unités), which was established so that scientists around the world could communicate efficiently with each other. Many countries have also adopted SI units for everyday use as well. The United States is one of the few countries that has not. Base SI Units Base (or basic) units, are the fundamental units of SI. There are seven base units, which are listed in . Chemistry uses five of the base units: the mole for amount, the kilogram for mass, the meter for length, the second for time, and the kelvin for temperature. The degree Celsius (°C) is also commonly used for temperature. The numerical relationship between kelvins and degrees Celsius is as follows: K = °C + 273 Table 1.2 The Seven Base SI Units Pr op ert y U n i t Ab bre via tio n le ng th m e t m
  • 39. 39 | P a g e Pr op ert y U n i t Ab bre via tio n e r m as s k i l o g r a m kg ti m e s e c o n d s a m ou nt m o l e mo l te m pe ra tu re k e l v i n K ele ctr ica l cu rr en t a m p e r e am p lu mi no us int en sit y c a n d e l a cd Note The United States uses the English system of units for many quantities. Inches, feet, miles, gallons, pounds, and so forth, are all units connected with the English system of units.
  • 40. 40 | P a g e The size of each base unit is defined by international convention. For example, the kilogram is defined as the quantity of mass of a special metal cylinder kept in a vault in France (). The other base units have similar definitions. The sizes of the base units are not always convenient for all measurements. For example, a meter is a rather large unit for describing the width of something as narrow as human hair. Instead of reporting the diameter of hair as 0.00012 m or even 1.2 × 10−4 m, SI also provides a series of prefixes that can be attached to the units, creating units that are larger or smaller by powers of 10. Figure 1.8 the Kilogram The standard for the kilogram is a platinum-iridium cylinder kept in a special vault in France. Source: Photo reproduced by permission of the Bureau International des Poids et Mesures, who retain full internationally protected copyright. Common prefixes and their multiplicative factors are listed in . (Perhaps you have already noticed that the base unit kilogram is a combination of a prefix, kilo- meaning 1,000 ×, and a unit of mass, the gram.) Some prefixes create a multiple of the original unit: 1 kilogram equals 1,000 grams, and 1 megameter equals 1,000,000 meters. Other prefixes create a fraction of the original unit. Thus, 1 centimeter equals 1/100 of a meter, 1 millimeter equals 1/1,000 of a meter, 1 microgram equals 1/1,000,000 of a gram, and so forth. Table 1.3 Prefixes Used with SI Units
  • 41. 41 | P a g e P r e f i x A b b r e v i a t i o n M u l t i p l i c a t i v e F a c t o r M u l t i p l i c a t i v e F a c t o r i n S c i e n t i f i c N o t a t i o n g i g a - G 1 , 0 0 0 , 0 0 0 , 0 0 0 × 1 0 9 × m e g a - M 1 , 0 0 0 , 0 0 0 × 1 0 6 × k i k 1 , 1 0
  • 42. 42 | P a g e P r e f i x A b b r e v i a t i o n M u l t i p l i c a t i v e F a c t o r M u l t i p l i c a t i v e F a c t o r i n S c i e n t i f i c N o t a t i o n l o - 0 0 0 × 3 × d e c a - D 1 0 × 1 0 1 × d e c i - d 1 / 1 0 × 1 0 − 1 × c e n t i - c 1 / 1 0 0 × 1 0 − 2 × m i l m 1 / 1 1 0 −
  • 43. 43 | P a g e P r e f i x A b b r e v i a t i o n M u l t i p l i c a t i v e F a c t o r M u l t i p l i c a t i v e F a c t o r i n S c i e n t i f i c N o t a t i o n l i - , 0 0 0 × 3 × m i c r o - µ * 1 / 1 , 0 0 0 , 0 0 0 × 1 0 − 6 × n a n o - n 1 / 1 , 0 0 0 , 0 0 0 1 0 − 9 ×
  • 44. 44 | P a g e P r e f i x A b b r e v i a t i o n M u l t i p l i c a t i v e F a c t o r M u l t i p l i c a t i v e F a c t o r i n S c i e n t i f i c N o t a t i o n , 0 0 0 × *The letter µ is the Greek lowercase letter for m and is called ―mu,‖ which is pronounced ―myoo.‖ Both SI units and prefixes have abbreviations, and the combination of a prefix abbreviation with a base unit abbreviation gives the abbreviation for the modified unit. For example, kg is the abbreviation for kilogram. We will be using these abbreviations throughout this book. Derived SI Units Derived units are combinations of SI base units. Units can be multiplied and divided, just as numbers can be multiplied and divided. For example, the area of a square having a side of 2 cm is 2 cm × 2 cm, or 4 cm2 (read as ―four centimeters squared‖ or ―four square centimeters‖). Notice that we have squared a length unit, the centimeter, to get a derived unit for area, the square centimeter.
  • 45. 45 | P a g e Volume is an important quantity that uses a derived unit. Volume is the amount of space that a given substance occupies and is defined geometrically as length × width × height. Each distance can be expressed using the meter unit, so volume has the derived unit m × m × m, or m3 (read as ―meters cubed‖ or ―cubic meters‖). A cubic meter is a rather large volume, so scientists typically express volumes in terms of 1/1,000 of a cubic meter. This unit has its own name—the liter (L). A liter is a little larger than 1 US quart in volume. ( gives approximate equivalents for some of the units used in chemistry.) As shown in , a liter is also 1,000 cm3 . By definition, there are 1,000 mL in 1 L, so 1 milliliter and 1 cubic centimeter represent the same volume. 1 mL = 1 cm3 Figure 1.9 The Liter A liter is defined as a cube 10 cm (1/10th of a meter) on a side. A milliliter, 1/1,000th of a liter, is equal to 1 cubic centimeter. Table 1.4 Approximate Equivalents to Some SI Units 1 m ≈ 39.36 in. ≈ 3.28 ft ≈ 1.09 yd 1 cm ≈ 2.54 in. 1 km ≈ 0.62 mi 1 kg ≈ 2.20 lb 1 lb ≈ 454 g 1 L ≈ 1.06 qt 1 qt ≈ 0.946 L Energy, another important quantity in chemistry, is the ability to perform work, such as moving a box of books from one side of a room to the other side. It has a derived unit of kg·m2 /s2 . (The dot between the kg and m units implies the units are multiplied together.) Because this combination is cumbersome, this collection of units is redefined as a joule (J). An older unit of energy, the calorie (cal), is also widely used. There are 4.184 J in 1 cal. All chemical processes occur with a simultaneous change in energy. (For more information on energy changes, see .) To Your Health: Energy and Food The food in our diet provides the energy our bodies need to function properly. The energy contained in food could be expressed in joules or calories, which are the conventional units for energy, but the food industry prefers to use the kilocalorie and refers to it as the Calorie (with a capital C). The average daily energy requirement of an adult is about 2,000–2,500 Calories, which is 2,000,000–2,500,000 calories (with a lowercase c).
  • 46. 46 | P a g e If we expend the same amount of energy that our food provides, our body weight remains stable. If we ingest more Calories from food than we expend, however, our bodies store the extra energy in high-energy-density compounds, such as fat, and we gain weight. On the other hand, if we expend more energy than we ingest, we lose weight. Other factors affect our weight as well—genetic, metabolic, behavioral, environmental, cultural factors—but dietary habits are among the most important. In 2008 the US Centers for Disease Control and Prevention issued a report stating that 73% of Americans were either overweight or obese. More alarmingly, the report also noted that 19% of children aged 6–11 and 18% of adolescents aged 12– 19 were overweight—numbers that had tripled over the preceding two decades. Two major reasons for this increase are excessive calorie consumption (especially in the form of high-fat foods) and reduced physical activity. Partly because of that report, many restaurants and food companies are working to reduce the amounts of fat in foods and provide consumers with more healthy food options. Density is defined as the mass of an object divided by its volume; it describes the amount of matter contained in a given amount of space. density=massvolume Thus, the units of density are the units of mass divided by the units of volume: g/cm3 or g/mL (for solids and liquids), g/L (for gases), kg/m3 , and so forth. For example, the density of water is about 1.00 g/cm3 , while the density of mercury is 13.6 g/mL. (Remember that 1 mL equals 1 cm3 .) Mercury is over 13 times as dense as water, meaning that it contains over 13 times the amount of matter in the same amount of space. The density of air at room temperature is about 1.3 g/L. Example 10 Give the abbreviation for each unit and define the abbreviation in terms of the base unit. kiloliter microsecond decimeter nanogram Solution The abbreviation for a kiloliter is kL. Because kilo means ―1,000 ×,‖ 1 kL equals 1,000 L. The abbreviation for microsecond is µs. Micro implies 1/1,000,000th of a unit, so 1 µs equals 0.000001 s. The abbreviation for decimeter is dm. Deci means 1/10th, so 1 dm equals 0.1 m. The abbreviation for nanogram is ng and equals 0.000000001 g. Skill-Building Exercise Give the abbreviation for each unit and define the abbreviation in terms of the base unit.