BASIC CHEMISTRY
Honors Biology
Recall: Levels of Organization
Biology Depends on Chemistry
 In our biosphere, everything is made of atoms
 Through the interaction of chemicals we can better
understand our biosphere
Give an example from what we have already done in Bio.
THE ATOM
2 MAIN AREAS
1.NUCLEUS
-center
2. ENERGY LEVELS
-outer circle(s)
THE ATOM
3 subatomic particles
(small pieces of the atom)
In the nucleus:
1. protons
2. neutrons
In the energy levels:
3. electrons
THE ELEMENT
A substance containing
only one type of atom
is:
ELEMENT
CARBON ATOM
PERIODIC TABLE
All known elements are
organized in the
periodic table.
The periodic table tells
you information about
each element
Information about elements
Elements are not charged, therefore electrons always equal protons.
Atomic Numbernumber of protons in the atom
Chemical Symbol
Atomic Massnumber of protons and neutrons
Find the following
If the atomic number for H is 1:
How many protons in H?
If the atomic mass of H is 1:
How many neutrons in H?
How many electrons?
Find the following
The atomic number for O is 8.
How many protons in O?
How many electrons in O?
The atomic mass of O is 16.
How many neutrons in O?
Draw an Oxygen atom. Show the
number of protons and neutrons in the
nucleus and the electrons in the energy
level.
Draw Nitrogen
Draw Carbon
 Nitrogen atomic number: 7 atomic mass: 14
 Carbon atomic number 6 atomic mass: 12
Molecules
 2 or more atoms
held together by
chemical bonds
THE COMPOUND
A substance containing
two different types of
atoms is:
CARBON ATOM
OXYGEN ATOM
COMPOUND
All compounds are
molecules but not all
molecules are compounds
What compound is this?
How many elements in each of the
molecules below?
How many atoms in each?
CO2 - carbon dioxide
H2O - water
C6H12O6 - sugar (glucose)
NaCl - salt
O2 - oxygen (usable)
Bonding
IONIC BOND
One atom gives
an electron to
another- this
causes a charge
in the atom
Charged atoms
are called ions.
Bonding
Atoms share electrons
in order to fill the
last energy level of
each
“co-” means share
Strong Bonds!
COVALENT
BOND
How many bonds can these make?
*How many electrons are needed to fill the outer energy level?
 Hydrogen
 Oxygen
 Nitrogen
 Carbon
Bonds these make
 Hydrogen - 1
 Oxygen - 2
 Nitrogen - 3
 Carbon - 4
Chemical Bonds: Hydrogen
 Weak bond formed from
the unequal sharing of
electrons
 Slightly positive, slightly
negative ends
 Importance to biology:
critical to water’s
properties, holds DNA
together
wh
Chemical Reactions

Synthesis
 Make a compound
 Ex: Photosynthesis

Decomposition
 Break down a compound
 Ex: Cellular Respiration

Both reactions important to biology:
metabolism
 Chemical reactions are
written like simple
addition problems.
H2 O3
H2 O + O2
Reactants (inputs):
what goes in to the
reaction
H2 O3
Products (outputs):
what comes out of
the reaction
H2 O + O2
The body is factory of chemicals
 Bonding takes place when chemicals react
 This is called a chemical reaction