Untitled - Kelly Walsh High School

Nuclear Chemistry 303
1. A typical periodic table always lists which of the following? (There may be
more than one correct answer.)
a. chemical symbol b. atomic number c. mass number
d. atomic weight e. physical state
2. Two atoms with the same number of protons but different numbers of neutrons
are examples of ______ of an element.
3. Write symbols for each of the following.
a. alpha particle b. beta particle c. gamma ray
d. positron e. electron f. proton g. neutron
4. Balance the following nuclear equations. Gamma rays are not necessary.
137
137
a. 58Ce
_____ l 57La
205 205
b. 80Hg
l 81Tl
_____
245 241
c. 96Cm
l 94Pu
_____
256
4
d. 103Lr
l _____ 2He
238 1 e. 92U
0n
l _____
5. If 6.25 % of a radioactive isotope remains after 40 days, what is the half-life
of the isotope?
6. a. Define fission. b. Define fusion.
7. The mass defect for helium-4 is 0.0304 g/mol. Determine the nuclear binding
energy in joules per mole for 1 mol of helium-4.
8. The half-life of krypton-85 is 10.76 years. What percentage of a sample of
krypton-85 will remain after 21.52 years?
9. After 182 min, the amount of arsenic-78 in a particular sample has
decreased from 5.00 mg to 1.25 mg. What is the half-life of arsenic-78?
10. A sample of hair from an Egyptian mummy gives off radiation from carbon-14
at a rate of 58.2 % of a present day sample. How old is the mummy if the
half-life of carbon-14 is 5730 years?
ANSWER KEY
1. a, b, and d. 2. isotopes
3. a. 4 4
2a
or 2He
0 0
b. 1b
or 1e
0 c. g or 0g
d. 0 0
1b
or 1e
0 e. 1e
1 1 f. 1p
or 1H
1 g. 0n
0 4. a. 1e
5. 10 days
0 b. 1b
4 4 c. 2He
or 2a
252 d. 101Md
239 e. 92U
6. a. Nuclear fission is the breakdown of a nucleus into two or more smaller
nuclei with the release of energy.
b. Fusion is the combining of lighter nuclei into a heavier one.