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Chemistry of Life
Chapter 3
Section 1: Matter and Substances
Atom – smallest unit of matter
3 Particles: Protons (+), Neutrons (0),
Electrons (-)
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Element – a substance made up of atoms
that cannot be separated
 Isotopes – atoms of an element that have
different #’s of neutrons
 Compound – a substance made up of
bonded atoms of 2 or more different
elements
 Valence Electrons – outermost electrons
 Molecule - group of atoms held together
by covalent bonds

2 Types of Chemical Bonds
1. Covalent – sharing valence electrons
Ex. Water (H2O)
2. Ionic – transferring electrons
Ex. Table Salt (NaCl)
Polarity – describes the positive or negative state
of a molecule
Polar – Water, salt, sugar (easily attracted
to each other)
Nonpolar – oil, grease
Solubility – capable of being
dissolved
Hydrogen Bonds – important in the bonding of
living things
Section 2: Water and Solutions
4 Properties of Water
1. Density – water is less dense as a solid than a
liquid (hydrogen bonds create empty spaces)
2. Water absorbs and retains heat (hydrogen
bonds constantly break & form)
3. Cohesion - water molecules stick to each other
4. Adhesion – water molecules stick to other polar
substances

Solution – an evenly dispersed mixture of
2 or more substances; some solutions
change the balance of ions (charged
particles)

Acid – any cmpd. that increases the # of
hydronium (H+) ions when dissolved in
water
 Example:

HCl in your stomach
Base – any cmpd. that increases the # of
hydroxide (OH-) ions when dissolved in
water
 Example:
ammonia (NH4+)
pH – measure of how acidic or basic a
solution is
 Buffer – substance that reacts to prevent
a pH change in a solution

Section 3: Carbon Compounds
Building Blocks of Cells include:
1. Carbohydrates – molecules made of sugars
Used for: sources of energy, structural materials,
cellular identification
2. Lipids – fat molecules
Used for: storing energy and controlling water
movement
3. Proteins – molecule made up of amino acids
Used for: provide structure/support, enable
movement or communication, and carry out
chemical reactions
4. Nucleic Acids – an organic cmpd. made of two
chains of sugar and carry genetic information
Used for: store and transmit hereditary
information

ATP – Adenosine triphosphate; acts as the
main energy source for cell processes
Section 4: Energy and Metabolism
Conservation of Mass – mass is neither
created or destroyed, only changed forms
 Conservation of Energy – energy is neither
created or destroyed, only changed forms

Chemical Reactions include:
 Reactant – substance that is changed in a
chemical reaction
 Product – new substance formed in a
chemical reaction



Activation Energy – minimum amount of energy
required to start a chemical reaction
Enzymes – molecules that speed up a reaction
sites – region where the reaction takes place
 Substrates – shape of active site that reactors will
bind to
 Active
Enzyme Action:
1. Substrates bind to enzyme’s active site
2. The enzyme changes shape, which
catalyzes (speed up) the reaction
3. Product is released when the reaction
is complete
Metabolism – the sum of physical and
chemical processes in an organism