Worksheet: Radioactive Decay and Half-life
Name:________________
Period:_________
Date:_________
1. Balancing the following nuclear reactions. Use nuclear notations for the unknowns.
0
a. 207
84 Po 1   _____
Es  24He 01n  _____
b.
253
99
c.
14
7
d.
249
99
258
Po  _____ 103
Lr  401n _____
e.
238
93
Np 10  _____
f.
239
96
g.
2
1
h.
238
92
i.
7
4
j.
131
53
N  24He 178O  _____
Cm126C 4 01n  _____
H 12H 01n  _____
U  12H 2 01n  _____
Be  10  _____
I  10  _____
2. Write balanced equations for the following nuclear reactions.
a. Uranium-233 undergoes one alpha decay
b. Neptunium-239 undergoes three alpha decays
c. Copper-66 undergoes two beta decays
d. Phosphorus-33 undergoes one beta decay
3. Write a balanced equation for the fission of uranium-235 by a neutron into uranium-236
which then further decays into barium-139, krypton-94, and three neutrons.
4. In solar fusion, four hydrogen nuclei (protons) combine with two beta particles to
produce an alpha particle. Write the balanced equation for that nuclear reaction.
5. A sample initially contains 60.0 grams of thorium-234. After 48 days, only 7.5 grams of
thorium remains. Determine the half-life.
6. Technetium-104 has a half-life of 18 minutes. Starting with an initial mass of 100.0
grams, how much would remain after 15.6 hours?
7. Manganese-56 is a beta emitter with a half-life of 2.6 hours. Starting with a 10.0 grams
sample, how much would remain after 15.6 hours?
8. F 20.0 grams of element Xenaium remains after 72 days, determine the mass of the
original sample. The half-life of Xenaium-234 is 12 days.