The document discusses the basic chemistry concepts that are essential for life, including the structure of atoms and molecules, chemical bonds, and chemical reactions. It also examines the organic compounds that are important for living things like carbohydrates, lipids, proteins, and nucleic acids. Furthermore, the document explains how enzymes are important biological catalysts that allow chemical reactions to occur efficiently in living cells.

1. Chapter 2
The Chemistry of Life

2. Section 1: The Nature of
Matter

3. Objectives
• What three subatomic particles make up
atoms?
• How are all the isotopes of an element
similar?
• What are the two types of chemical
bonds?

4. The Big Idea
• Life Depends on chemistry
• Chemical reactions keep you
alive

5. Atom
• Basic unit of matter

6. Democrites

7. Subatomic particles
• Protons - Positively charged (+) Bind together
to form the
• Neutrons - Not charged (neutral) nucleus
• Electrons - Negatively charged (-)
Protons
Electrons Nucleus
Neutrons

9. Element
• A pure substance that consists
of just one type of atom

11. An elements atomic number = number of
protons
Atomic number
6
C
Carbon
12.011

12. Isotope
• Atoms of the same element
that differ in the number of
neutrons they contain

13. Nonradioactive carbon-12 Nonradioactive carbon-13 Radioactive carbon-14
6 electrons 6 electrons 6 electrons
6 protons 6 protons 6 protons
6 neutrons 7 neutrons 8 neutrons

14. The Sum of protons and neutrons in the nucleus of an
atom is its mass number
6
C
Carbon
Mass number
12.011

15. • The weighted average of the
masses of an elements isotope is
called its atomic mass

16. Radioactive isotopes
• Can be dangerous
• Can be used
practically
– Radioactive dating
– Treat cancer
– Kill bacteria

17. Compounds
• A substance formed by the
chemical combination of two or
more elements in definite
proportions
• Ex) H2O, NaCl

22. Table Salt

23. Ionic Bonds
• Formed when one or more
electrons are transferred from
one atom to another

24. Sodium atom (Na) Chlorine atom (Cl) Sodium ion (Na+) Chloride ion (Cl-)
Transfer
of electron
Protons +11 Protons +17 Protons +11 Protons +17
Electrons -11 Electrons -17 Electrons -10 Electrons -18
Charge 0 Charge 0 Charge +1 Charge -1

25. • If an atom loses an electron it
becomes positive
• If an atom gains an electron it
becomes negative

26. Ions
• Positively and negatively
charged atoms

28. Covalent Bonds
• Forms when electrons are
shared between atoms

30. Molecule
• The structure that results when
atoms are joined together by a
covalent bond
• Smallest unit of most compounds

31. Van der Waals Forces
• A slight attraction that
develops between the
oppositely charged regions of
nearby molecules due to
unequal sharing of electrons

34. Homework

35. 1. Describe the structure of an atom.
Atoms are made up of protons and
neutrons in a nucleus. Electrons are
in constant motion in the space
around the nucleus.
2. Why do all isotopes of an element
have the same chemical properties
They have the same number of
electrons

36. 3. What is a covalent bond?
A bond formed when electrons are
shared between atoms
4. What is a compound? How are they
related to molecules
A compound is a substance formed
by the chemical combination of two or
more elements in definite proportions.
A molecule is the smallest unit of
most compounds

37. 5. How do Van der Waals forces
hold molecules together?
When the sharing of electrons
are unequal, a molecule has
regions that are charged. An
attraction can occur between
oppositely charged regions of
nearby molecules

38. 6. How are ionic bonds and Van
der Waals forces similar? How
are they different?
In both cases, particles are
held together by attractions
between opposite charges.
The difference is that ionic
charges are stronger

39. Section 2: Properties of
Water

40. Objectives
• Why are water molecules polar?
• What are acidic solutions? What
are basic solutions?

41. The Big Idea
• Much of our planet is covered in
water
• Water is necessary for life to exist
• If life exists on other planets,
there most likely is water present
• Water has many properties that
make life possible

42. Polarity
(-) The oxygen atom has
a stronger attraction for
electrons
(+)

43. Hydrogen Bonds
• Because of waters partial
charges, they can attract each
other and create hydrogen bonds
• Not as strong as covalent or ionic
bonds
• Waters ability to create multiple
hydrogen bonds gives it many
special properties

44. Cohesion
• Attraction between molecules of
the same substance

47. Adhesion
• Attraction molecules of different
substances

49. Mixture
• Material composed of two or more
elements or compounds that are
physically mixed but not
chemically combined
• Ex.) salt & pepper, earths
atmosphere

50. Solutions
• Mixture of two or more
substances in which the
molecules are evenly distributed
• Ex.) salt water
• Settles out over time

51. Solutions
Cl-
Cl- Na+
Na+
Water
Water

52. Solute
• Substance that is dissolved
• Ex.) salt

53. Solvent
• The substance that does the
dissolving
• Ex.) Water

54. Suspensions
• Mixture of water and non-
dissolved materials
• Ex.) sugar solution, blood
• Separate into pieces so small,
they never settle out

55. The pH scale
• Indicated the concentration of
hydrogen ions in a solution

56. Acid
Neutral
Base

57. Acids
• Any compound that forms H+
(hydrogen) ions in solution

58. Base
• A compound that produces OH-
(hydroxide) ions in solution

59. Buffers
• Weak acids or bases that can
react with strong acids or bases
to prevent sharp, sudden pH
changes

60. Homework

61. 1. Use the structure of a water
molecule to explain why its polar
Oxygen atom has greater
attraction for electrons, therefore
the oxygen atom is negative and
the hydrogen end is positive

62. 2. Compare acidic and basic
solutions in terms of their H+ ion
and OH- ion concentrations
Acid have more H+ ions than OH-
ions, and bases have more OH-
ions than H+ ions

63. 3. What is the difference between a
solution and a suspension?
In a solution, all components are
evenly distributed. In a
suspension, un-dissolved
particles are suspended

64. 4. What does pH measure?
The concentration of H+ ions in a
solution
5. The strong acid hydrogen floride
(HF) can be dissolved in pure
water. Will the pH of the solution
be greater or less than 7?
less than 7

65. Section 3: Carbon Compounds

66. Objective
• What are the functions of each
group of organic compounds?

67. Interest Grabber
Section 2-3 Life’s backbone
• Most of the compounds that make up living
things contain carbon. In fact, carbon makes
up the basic structure, or “backbone,” of these
compounds. Each atom of carbon has four
electrons in its outer energy level, which
makes it possible for each carbon atom to
form four bonds with other atoms.
• As a result, carbon atoms can form long
chains. A huge number of different carbon
compounds exist. Each compound has a
different structure. For example, carbon chains
can be straight or branching. Also, other kinds
of atoms can be attached to the carbon chain.

68. Methane Acetylene Butadiene Benzene Isooctane

69. Macromolecules “giant molecules”
• Formed by a process called
polymerization

70. Monomers
• Smaller units

71. Polymers
• Linked up monomers

72. Carbohydrates
• Compounds made up of carbon,
hydrogen, and oxygen atoms
usually in a ratio of 1:2:1
• Main source of energy
• The monomers of starch are
sugars

73. • Single sugar molecules are called
monosaccharides
• The large macromolecules formed
from monosaccharides are known
as polysaccharides

74. Starch
Glucose

75. Lipids
• Made mostly from carbon and
hydrogen atoms
• Used to store energy

76. Lipid Glycerol
Fatty Acids

77. Proteins
• Macromolecules that contain
nitrogen as well as carbon,
hydrogen, and oxygen
• Proteins are polymers of
molecules called amino acids

78. Amino Acids
Carboxyl group
General structure Alanine Serine

79. • More than 20 different amino
acids, can join to any other amino
acid
• The instructions for arranging
amino acids into many different
proteins are stored in DNA
• Each protein has a specific role
• The shape of proteins can be very
important

80. Proteins
Amino
Acids

81. Nucleic Acids
• Macromolecules containing hydrogen,
oxygen, nitrogen, carbon, and
phosphorus
Double
Helix

82. Nucleotides
• Consists of 3 parts: 5-carbon sugar,
phosphate group and nitrogen base
Nitrogen Base
Phosphate
group
5-Carbon Sugar

83. 2 kinds of nucleic acids
• RNA (ribonucleic acids) –
contains sugar ribose
• DNA (deoxyribonucleic acid) –
contains sugar deoxyribose

84. Homework

85. 1. Name four groups of organic compounds
found in living things
carbohydrate, lipid, protein, nucleic acids
2. Describe at least one function of each
group of organic compounds
carbohydrates – energy
lipids – store energy
proteins – form tissue
nucleic acids – transmit hereditary
information

86. 3. Compare the structures and
functions of lipids and starches
Lipids are made from carbon and
hydrogen. Starches are made of
carbon, hydrogen and oxygen.
They both can be used to store
energy

87. Section 4: Chemical
Reactions and Enzymes

88. Objectives
• What happens to chemical bonds
during chemical reactions?
• How do energy changes affect
whether a chemical reaction will
occur?
• Why are enzymes important to
living things?

89. The Big Idea
• Living things are made up of
chemical compounds
• Everything that happens to an
organism is based on chemical
reactions

90. Chemical Reactions
• A process that changes or
transforms one set of chemicals
into another

91. Reactants
• Elements or compounds that
enter into a reaction

92. Products
• Elements or compounds
produced by a chemical reaction

93. Example Reaction: Getting
rid of carbon dioxide
• In the blood
CO2 + H20  H2CO3 (carbonic acid)
• In the lungs
H2CO3  CO2 + H2O
Released as you
breathe

94. Energy in reactions
Energy-Absorbing Reaction Energy-Releasing Reaction
Products Activation
energy
Activation energy
Reactants
Reactants
Products

95. Activation Energy
• The energy that is needed to get
a reaction started

97. Enzymes
• Some chemical reactions are too
slow or have activation energies
that are too high to make them
practical for living tissue
• These chemical reactions are
made possible by catalysts

98. Catalyst
• Substance that speeds up the
rate of chemical reactions
• Work by lowering a reactions
activation energy

99. Enzyme
• Biological catalysts
• Speed up reactions in cells
• Very specific
• Named for the reaction is catylzes
• Enzyme names always end in
-ase

100. Reaction pathway
without enzyme Activation energy
without enzyme
Reactants Activation
energy
Reaction pathway
with enzyme
with enzyme
Products

101. Substrates
• The reactants of enzyme
catalyzed reactions
• The active site of the enzyme and
the substrate have
complementary shapes
• Fit like a lock and key

102. Enzyme Action
Enzyme – substrate complex

103. Enzyme
ADP (hexokinase) Glucose
Substrates
Products
ATP
Glucose-6-
phosphate
Products Active site
are released
Substrates
Enzyme-substrate bind to
complex
enzyme
Substrates
are converted
into products

104. Regulation of Enzyme Activity
• Enzymes are affected by any
variable that affects chemical
reactions
1. pH
2. Temperature
3. Concentration
of enzyme

106. Homework

107. 1. What happens to chemical bonds
during chemical reactions
Bonds are broken in reactants and
new bonds are formed in products
2. Describe the role of energy in
chemical reactions
some chemical reactions release
energy, and other chemical
reactions absorb energy. Energy
changes determine how easily a
chemical reaction will occur

108. 3. What are enzymes, and how are
they important to living things?
Enzymes are biological catylasts.
Cells use enzymes to speed up
virtually every important chemical
reaction that takes place in cells

109. 4. Describe how enzymes work,
including the role of the enzyme
substrate complex
Substrates, the reactants of an
enzyme-catylzed reaction, attach
to the enzyme at an active site
and form an enzyme – substrate
complex. Once the complex is
formed, the enzyme helps convert
substrate into product

110. 5. A change in pH can change the
protein. How might a change in pH
affect the function of an enzyme such
as hexokinase (hint: think about the
analogy of the lock and key)
A change in pH could change the
shape of hexokinase. This change
would diminish the ability of glucose
and ATP to bind to the active site of
the enzyme.