Name _____________________
CHEM 1004
Homework #12
Fall 2010 (Buckley)
This homework is due on Monday, December 6, at class time.
1. (5 points) Fill in the missing particle in each of the following equations. Be sure to
include its mass number and atomic number.
32
16
7
4
Sn  01n  11 p  ______
Be  10 e  _______
0
______  187
76 Os  1 e
98
42
Mo  12 H  01n  _______
1
U  01n  135
54 Xe  2 0 n  _______
235
92
2. (2 points) An important use of americium-241 is in smoke detectors. What particle is
emitted when americium-241 decays to neptunium-237?
3. (3 points) The half-life of tritium (hydrogen-3) is 12.3 years. If 60 mg of tritium is
released from a nuclear power plant, how many mg remain after:
a. 12.3 years
b. 61.5 years
c. 123 years
4. Iodine-131 is commonly used in treatment and diagnosis of thyroid issues.
a. Write the nuclear equation for the decomposition of iodine-131 through β particle
emission.
b. The half-life of iodine-131 is 8 days. If the patient initially has a dose of 10 mg of
iodine-131, how much would remain after 24 days?
c. If the level had to get down to 0.078 mg from 10 mg for the patient to be
considered “safe”, how many days would it take to be safe?