1. Chapter 2

2. Organisms are chemical machines
 All organisms consist of atoms
– Subatomic particles
 Electron (e-) – located in electron cloud
 Proton (p+) – located in the nucleus
 Neutron (no) – located in the nucleus
Oxygen atom (O)
Nucleus:
8 protons (+)
8 neutrons
outermost energy
level:
6 electrons (-)
inner energy level:
2 electrons (-)

4. – Differ in the number of protons in the
nucleus.
– Number of protons = Number of
electrons
 Elements are neutral on the periodic table
– Atomic Number = Number of protons
– Atomic Mass = Number of protons + Number
of neutrons
http://www.privatehand.com/flash/elements.html

5. Name Symbol # p+ # e- #no
Tin
25
N
15
12

6. Differ in the number of neutrons they
contain in the nucleus
– Example:
 Carbon 12 – 6p+, 6e-, 6no
 Carbon 13 – 6p+, 6e-, 7no
 Carbon 14 – 6p+, 6e-, 8no

7.  Chemical Bonding – Compounds are
made of joined atoms of two or more
different elements.
 Valence shell – outermost electron shell
– Atoms with a full valence shell are inert
(unreactive)
– Atoms without a full valence shell can form bonds
(reactive).

8. Name Symbol # p+ # e- #no
Oxygen
6
K
53
- Why do all isotopes of an element have the same chemical
properties? (Use your book to help you answer this)

9.  The first electron shell of every atom can
hold a maximum of 2 electrons.
 Each additional shell can hold a maximum
of 8 electrons.

10. 1. Fluorine
2. Boron
3. Sodium

11.  Covalent bonds – atoms share
electrons
– Ex: H2, O2, CO2
covalent bonds
Oxygen atom (O) Carbon atom (C) Oxygen atom (O)
Carbon dioxide (CO2 )

12.  Ionic Bonds – atoms gain or loose
electrons
– Atoms form ions
 + charge – cation
 - charge – anion
 Ex: NaCl

13.  Hydrogen Bonds – weak chemical
attraction between polar molecules
– Water is a polar molecule because the electrons
of O and H are shared unequally.

15. • 70% of your body is made of water.
• The remaining 30% is made up mostly of
organic compounds (Carbon-based
molecules).
– Carbon is a unique element because it forms four
covalent bonds and can form a lot of different
structures.

16. Many carbon-based molecules are made of
many small subunits bonded together.
– Monomers are the individual subunits.
– Polymers are made of many monomers.

17.  Key source of energy found in
most foods
 Fruits, vegetables, and grains
 Made up of single sugars called
monosaccharides.
 Glucose, fructose
 Disaccharides - two
monosaccharides are joined
 Sucrose (table sugar)
 Polysaccharides – chains of three
or more monosaccharides
 Starch, cellulose, glycogen

18. Polymer (starch)
Starch is a polymer
of glucose monomers
that often has a
branched structure.
Polymer (cellulose)
Cellulose is a
polymer of glucose
monomers that has a
straight, rigid
structure
monomer

19.  Nonpolar molecules not soluble in water
 Fats, phospholipids (make up the cell membrane),
steroids (cholesterol), waxes
 Saturated fatty acids
 Solid at room temperature
 Butter, lard, grease
 Unsaturated fatty acids
 Liquid at room temperature
 Olive oil, fish oil

21.  Formed by chains of linked amino acids
 Many functions including:
 Enzymes
 Structural (imbedded in the cell membrane)
 Antibodies

22.  Formed by chains of nucleotides
 Two types :
 DNA (deoxyribonucleic acid)
 Double strand of nucleotides
 Stores hereditary information
 RNA (ribonucleic acid)
 Single strand of nucleotides
 Plays a key role in making proteins
Nucleotide

24. Another important biological molecule
 ATP (adenosine triphosphate)
– Consists of a single nucleotide with 2 extra
phosphate groups.
– ATP stores energy temporarily.
– All cells require ATP to function.

25. Chemistry allows life to function!
Everything living things do is possible due
to chemical reactions
The chemistry of
breathing

26. Activation energy is the amount of energy
that needs to be put in to start a chemical
reaction.

27. Exothermic reactions release more energy
than they absorb.
– Excess energy is released by the reaction as
heat.

28. Endothermic reactions absorb more energy
than they release.
– Energy is absorbed by the reaction.

29. – Proteins that increases the speed of a
chemical reactions in cells
– Act as a catalyst (reduces the activation energy
needed in a reaction)

30.  Any factor that changes the shape of an
enzyme can affect the enzyme’s activity.
– An enzyme’s function depends on its structure.
– Denaturing (changing the structure) the protein by
changes in temperature or pH
– Example: pepsin