Nuclear Decay Equations
Type of Decay
Notation
Strength
Alpha
α or 42He
weak
Beta
β- or
0
Gamma
medium
0
-1e
strong (like an X-ray)
0γ
What does it mean if something is decaying?
Natural Nuclear Decay is when:
ALPHA DECAY
An alpha particle is a ___________ nucleus, with ____ protons and ____ neutrons.
Because the alpha particle contains _____ protons, when an atom releases an alpha particle, its
atomic number would decrease by __________. This means it is a new element!
Consider Carbon-12:
Before decay
Number of protons
Number of neutrons
Total mass
12
C
After alpha decay
Number of protons (-2)
Number of neutrons (-2)
Total mass (-4)
What happened to the atomic number? ______________________________
What happened to the mass number? _______________________________
The equation for this decay looks like this:
12
6C

4
2He
+
Complete this example:
226
88Ra

4
2He
+
NOTICE that the sum
of atomic and mass
number on the left
side of the equation
equals the sum of
the atomic and mass
number on the right
side of the equation.
BETA DECAY
A beta particle is equivalent to an _______________. (A neutron splits, leaving a proton behind).
n  p + eWhen an atom releases a beta particle, its atomic number would increase by __________. This means
it is a new element!
Consider Carbon-14:
Before decay
Number of protons
Number of neutrons
Total mass
14
C
After beta decay
Number of protons (+1)
Number of neutrons (-1)
Total mass (+0)
What happened to the atomic number? ______________________________
What happened to the mass number? _______________________________
The equation for this decay looks like this:
14
6C

0
-1e
+
Complete this example:
131
53I

0
-1e
+
GAMMA DECAY
A gamma ray is ______________, (not a particle) resulting from an energy change within the
nucleus. It has _____ mass or charge. Gamma radiation doesn’t change the state of the
nucleus, it just carries some energy away. Gamma rays are emitted along with alpha or beta
particles.