Nuclear Chemistry
Natural Radioactivity
 The
spontaneous breakdown of
atomic nuclei, accompanied by
the release of some form of
radiation
Transmutation: the conversion of
one element to another by means of
a nuclear change
To detect Radioactivity one could
use Geiger Counter
Types of Radioactive Emissions
All differ in mass, size and charge
 Reference Table O

Alpha Particle:
2
positive 2 charge
helium nucleus
mass of 4amu
Ex: 22688Ra  22286Rn +
4
4
2He
Particle: 0-1
negative charge
acts like a high speed electron
no mass
 Example: 23592U  23593Np + 0-1
Beta
 Gamma
Radiation (NOT a Particle)

no charge
acts like a high speed x-ray but
with a lot more energy
no mass
Positron Particle: 0+1
positive 1 charge
acts like positive electrons
no mass
Charge
Relative
Penetrating
Power
Particle
Symbol
Mass
Alpha
4 
2
4amu +2
Low
Beta
0 
-1
0
-1
Moderate
Gamma
0 
0
0
0
High
Positron
0 
+1
0
+1
Moderate

Separation of Radioactive emissions by
charge:
Positively Charged Plate

+
+
+
+
Negatively Charged Plate


-
Half-Life

The time it takes for half of the
atoms in a given sample of an
element to decay.

Some selected half-lives are found on
Table N
All reactions on Table N are Natural
Transmutation
Formulas for half-life reactions are found
on Table T


Artificial Radioactivity

Artificial Transmutation: artificial
radioactivity produced by
bombarding the nuclei of stable
atoms with high energy particles,
thereby producing radioactive atoms
Fission Reactions

The splitting of an atomic nucleus
into two smaller nuclei by
bombardment of a neutron
(Nuclear Bomb). *Nuclear
Reactors are fission reactors.

Example: 23592U + 10n 
+ 3(10n) + Energy
142
191 Kr
Ba
+
56
36
Fusion Reactions

A nuclear reaction in which two or
more light nuclei combine to form a
single nucleus. Requires huge
amounts of pressure and extremely
high temperatures. Produces
much more energy than fission.
Occurs naturally on the sun. (Hbomb)

Example:
2
2 H 
H
+
1
1
4
2He
+ Energy
Uses of Radioactive Isotopes

Lab: To trace chemical reactions.

Industry: Radiating food to
preserve by killing bacteria, mold,
insect eggs.
Medicine

Must have relatively short halflives and be quickly eliminated
from the body.
 I-131 diagnosing and treating
Thyroid conditions (half-life
8.07 days)

Co-60 emits large amounts of
gamma radiation as it decays,
these rays can be aimed at
cancerous tumors (half-life 5.26
years)
Ra-226 used in treatment of certain
cancers (half-life 1600 years)
Tc-99 used in diagnosis of brain
tumors (half-life 2.13x105 years
Geology
 Fossils
C-14 to C-12 ratio (while alive
they are in equal amounts, once an
organism dies C-14 is no longer
taken in).
Rocks U-238 to Pb-206 ratio (U-238
decays through a series of steps until
it forms stable Pb-206. As time
passes, the amount of U-238
decreases while the amount of
Pb-206 increases).
Balancing Nuclear Equations

Steps for Balancing:
 Due
to the Law of the
Conservation of Matter, whatever
is on the left side of the equation
must also be on the right side of the
equation.
Add the mass numbers on the left
side of the equation, this MUST
equal the total mass numbers of the
right side of the equation.

Add the atomic numbers on the left
side of the equation, this MUST
equal the total atomic numbers on
the right side of the equation.

Example:
32
1 n 
S
+
16
0
1
32 P
H
+
1
15