Chapter 2
 The smallest particle of an element
that has the chemical properties of
the element.

Three subatomic particles:
 Protons: + charge
Equal mass; Found in
 Neutrons: no charge
the Nucleus
 Electrons: - charge; in constant movement around the
Nucleus

# protons = # electrons, so the atom is neutral
overall.
Amazing Atoms

A pure substance that consists entirely of one
type of atom.
 Listed on the periodic table.
 Ex: hydrogen (H)

Contain same number of protons &
electrons (so are the same element), but
have a differing number of neutrons.
 Ex: carbon-12 & carbon-14

Two or more elements chemically combined
together.
 The chemical and physical properties of a
compound are different than the properties of the
individual elements from which it is formed.
▪ Ex: NaCl

Two types:
 Ionic: Electrons are transferred from one atom to
another; creates ions
▪ Ions: charged atoms
▪ Ex: Na+, Cl Covalent: Electrons are
shared (travel around
both nuclei); creates
molecules
▪ Molecules: smallest unit of a compound with
covalent bonds
▪ Ex: H2O (2 atoms of H, 1 atom of O)
A Good Review


Composed of two or more elements or
compounds.
NOT chemically combined.

Solution: a mixture with components evenly
distributed throughout

Two parts:
 Solute: the part that is dissolved
 Solvent: the part that is dissolving

Acids: form H+ ions in a solution
 pH = 1-7

Bases: form OH- in a solution
 pH = 7-14

Buffers: weak acids or bases that react with
strong acids or bases to prevent sudden
changes in pH
 Help maintain homeostasis!

Carbon has 4 electrons for bonding, so it can
form strong covalent bonds with many other
elements (like H, O, P, S, and N).

Carbon can form single, double and triple
bonds with itself.

Organic = contains Carbon



Monomers: smaller unit
Polymers: larger compound
Types of Macromolecules: carbohydrates,
lipids, nucleic acids, proteins
Chemical Composition
-C, H, O
Examples
Function in Living Things
- monosaccharides: - Main source of
simple sugars
energy.
( glucose, fructose,
galactose)
- Structural
purposes in some
- polysaccharides: cells (cellulose in
complex sugars
plants).
(glycogen, starch)
Chemical Composition
Examples
Function in Living Things
-C, H, O
-fats, oil, waxes
-Stored energy.
- Glycerol + fatty
acid
-saturated: all
single bonds
(animal fats = bad!)
-Membranes &
waterproof
coverings.
-unsaturated: at
least one double
bond (vegetable
fats = good!)
-Chemical
messengers
(steroids).
Chemical Composition
-C, H, O, N, P
- sugar + phosphate
group (P) +
nitrogenous base
(N)
- polymers of
nucleotides
Examples
- DNA, RNA
Function in Living Things
- Store & transmit
genetic
information.
Chemical Composition
-C, H, O, N, S
- polymers of amino
acids
Examples
- enzymes
Function in Living Things
- Control reactions
(enzymes) & cell
processes.
- Transport
materials in & out of
cells.
- Fight disease
(antibodies).

When one set of chemicals changes into
another set of chemicals.
CO2 + H2O  H2CO3

Chemical reactions always involve the
breaking of bonds in the reactants and
the formation of new bond in the
products.
CO2 + H2O  H2CO3

Reactants: elements or compounds that
enter into a reaction
 Ex: CO2 & H2O

Products: elements or compounds that are
produced by a reaction
 Ex: H2CO3
2HCl + 2Na -> 2NaCl + H2

Remember the 2 after H2, means that there
are 2 atoms of H in this molecule. (For H2O,
there are 2 atoms of H and 1 atom of O.)

The 2 in front of 2HCl, means that there is 2
of the entire molecule, so 2 atoms of H and 2
atoms of Cl.



Reactions that release energy often occur
spontaneously.
Reactions that absorb energy will not occur
without a source of energy.
Activation Energy: the energy needed to get
a reaction started

Catalyst: a substance that speeds up the rate
of a chemical reaction by lowering the
activation energy.

Enzymes: proteins that act as catalysts in
cells.
Substrates: the reactants of an enzymecatalyzed reaction
Active site: spot on the enzyme where the
substrate binds


Video

Temperature, pH and regulatory molecules
can affect the activity of enzymes.

Dehydration synthesis: two molecules bond
together & H2O is made
 Used to make polysaccharides, lipids
& proteins

Hydrolysis: H2O is used to split two
molecules