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)
8 protons (+)
6 electrons (-)
inner energy level:
2 electrons (-)
– Differ in the number of protons in the
– Number of protons = Number of
Elements are neutral on the periodic table
– Atomic Number = Number of protons
– Atomic Mass = Number of protons + Number
Name Symbol # p+ # e- #no
Differ in the number of neutrons they
contain in the nucleus
Carbon 12 – 6p+, 6e-, 6no
Carbon 13 – 6p+, 6e-, 7no
Carbon 14 – 6p+, 6e-, 8no
Chemical Bonding – Compounds are
made of joined atoms of two or more
Valence shell – outermost electron shell
– Atoms with a full valence shell are inert
– Atoms without a full valence shell can form bonds
Name Symbol # p+ # e- #no
- Why do all isotopes of an element have the same chemical
properties? (Use your book to help you answer this)
The first electron shell of every atom can
hold a maximum of 2 electrons.
Each additional shell can hold a maximum
of 8 electrons.
Covalent bonds – atoms share
– Ex: H2, O2, CO2
Oxygen atom (O) Carbon atom (C) Oxygen atom (O)
Carbon dioxide (CO2 )
Ionic Bonds – atoms gain or loose
– Atoms form ions
+ charge – cation
- charge – anion
Hydrogen Bonds – weak chemical
attraction between polar molecules
– Water is a polar molecule because the electrons
of O and H are shared unequally.
• 70% of your body is made of water.
• The remaining 30% is made up mostly of
organic compounds (Carbon-based
– Carbon is a unique element because it forms four
covalent bonds and can form a lot of different
Many carbon-based molecules are made of
many small subunits bonded together.
– Monomers are the individual subunits.
– Polymers are made of many monomers.
Key source of energy found in
Fruits, vegetables, and grains
Made up of single sugars called
Disaccharides - two
monosaccharides are joined
Sucrose (table sugar)
Polysaccharides – chains of three
or more monosaccharides
Starch, cellulose, glycogen
Starch is a polymer
of glucose monomers
that often has a
Cellulose is a
polymer of glucose
monomers that has a
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
Formed by chains of linked amino acids
Many functions including:
Structural (imbedded in the cell membrane)
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
Another important biological molecule
ATP (adenosine triphosphate)
– Consists of a single nucleotide with 2 extra
– ATP stores energy temporarily.
– All cells require ATP to function.
Chemistry allows life to function!
Everything living things do is possible due
to chemical reactions
The chemistry of
Activation energy is the amount of energy
that needs to be put in to start a chemical
Exothermic reactions release more energy
than they absorb.
– Excess energy is released by the reaction as
Endothermic reactions absorb more energy
than they release.
– Energy is absorbed by the reaction.
– Proteins that increases the speed of a
chemical reactions in cells
– Act as a catalyst (reduces the activation energy
needed in a reaction)
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