BIOL 1201
CHEMISTRY REVIEW (1/16/08)
I. Scientific Notation
1.
Scientists usually express very large or very small numbers in scientific notation or
exponential notation. Numbers expressed in scientific notation have 1 digit to the left
of the decimal point multiplied by 10 raised to the appropriate exponent.
a.
A mass of 1,254 grams would be expressed as 1.254 x 10
3
grams.
i.
Since this is based units of ten the exponent equals the number of
places to the right or left the decimal point has been moved.
b.
A volume of 0.000345 mL would be expressed as 3.45 x 10
4
mL.
2.
This makes comparing numbers much easier because the exponents can be compared
quickly to see which is bigger.
II.
Logarithms
1.
Many biological processes or concepts, such as pH, and population growth, involve
logarithmic scales. In any logarithmic scale a number equals the logarithmic base
raised to an exponent:
Number = base
logarithm
2.
In science the most commonly used logarithmic base is 10. This means that scale very
similar to scientific notation.
a.
Example 1
10,000 = 10
4
So the log of 10,000 in the base 10 is 4
b.
Example 2
100 = 10
2
The log of 100 in the base 10 is 2.
III.
Atomic Structure
1.
Matter
is anything which takes up space and has mass. All matter on Earth is
composed of elements.
2.
Elements
are matter that can not be broken down into other substances by chemical
reactions.
3.
An atom
is the smallest unit of an element that retains all of the properties of that
element. Glucose is a substance that is composed of three elements Carbon, Hydrogen,
and Oxygen.
a.
There are 92 naturally occurring elements. Elements differ from one another in
terms of the number of subatomic particles contained in these atoms.
b.
Atoms are generally composed of three different types of subatomic particles
(Protons, Neutrons, and Electrons).
i.
Protons
are particles which have a mass of approximately 1 dalton (a
unit of atomic mass) and a charge of +1.
ii.
Neutrons
are particles which have a mass of approximately 1 dalton
and no charge.
iii.
Electrons
are particles with almost no mass (it is about 1/2000th of
either a proton or neutron) and a charge of 1.
iv.
The protons and neutrons are found in the nucleus of the atom with the
electrons orbiting this nucleus.
v.
The atoms of different elements can be distinguished from one another
on the basis of their Atomic Number (the number of protons in the
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CHEMISTRY REVIEW (1/16/08)
nucleus) and Atomic Mass (the sum of the masses of all the subatomic
particles in the atom).
1.
Atomic Number
= # of protons
2.
Atomic Mass
= is approximately the # of protons and neutrons
Particle
Mass
Charge
proton
~1 dalton
+1
neutron
~1 dalton
0
electron
~0 dalton
1
Element
Protons
Neutrons
Electrons
Atomic
Number
Atomic
Mass
Hydrogen
1
0
1
1
~1 (1.008)
Helium
2
2
2
2
~4 (4.0026)
Carbon
6
6
6
6
~12 (12.0011)
Nitrogen
7
7
7
7
~14
Oxygen
8
8
8
8
~16 (15.994)
IV.
Isotopes
1.
Different forms of an element. Isotopes have the same atomic number, but a different
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 Spring '07
 Wishtichusen
 Atom, Electrons, Chemistry Review

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