Atomic Theory WS 5
Nuclear Chemistry Review Sheet
A.
Completion
Use this completion exercise to check your knowledge of the terms and your understanding of the
concepts introduced in this unit. Each blank can be completed with a term, short phrase, or number.
Isotopes with unstable nuclei are radioactive. The nuclei of these radioisotopes decay
to stable nuclei plus radiation. The radiation may be alpha, beta, or gamma. Alpha
radiation consists of positively-charged particles (helium nuclei) that are easily stopped by a sheet of paper.
Beta radiation is composed of fast-moving particles, which are electrons, and therefore have almost no
mass. Gamma radiation is a form of electromagnetic radiation which has much more energy
than alpha or beta radiation. Gamma radiation has no mass nor charge. Two other
types of radiation , positron emission and electron capture reduce the neutron:proton ratio in the nucleus.
Nuclear fission occurs when fissionable isotopes are bombarded with neutrons. An
example is U- 235, but not U- 238. Plutonium, an element artificially-produced from uranium238, responds the same way. The radioisotopes split into many fragments, many of which are also
radioactive. In the process they produce more neutrons, which maintain the reaction, and
energy which can be harnessed.
In nuclear fusion, small nuclei fuse to make larger nuclei. The sun’s
radiation is produced when hydrogen nuclei fuse to make helium nuclei. Fusion
releases even more energy than fission, but it usually does not release radioactivity.
Nuclear bullets are used to make new elements in the lab. The superheavy elements are made
by smashing the nuclei of smaller elements together.
B.
True-False
Classify each of these statements as always true (AT); sometimes true (ST); or never true (NT).
__ST___ 1. Beta radiation is emitted when a radioisotope decays.
__NT___2. Gamma radiation has a negative charge. (no charge)
__AT___ 3. Gamma radiation is high-energy electromagnetic radiation.
__NT__ 5.
238
92U
+
0
-1

239
92U.
(Bi-238)
Atomic Theory WS 5
__NT__ 6. In nuclear fusion the nuclei of two very large smaller atoms fuse to make a heavier nucleus.
__NT_ 7. The products of nuclear fission are never radioactive. (always)
__AT__ 8. When a beta particle is emitted, the atomic number increases by 1, and the mass number stays
the same.
__NT__ 9. When a radioactive nucleus emits an alpha particle, its atomic number decreases by 4, and its
mass number decreases by 2. (opposite)
__NT_ 10. When a gamma ray is emitted, the atomic mass and atomic number both increase. (neither)
__AT_ 11. Transuranium elements have atomic numbers greater than 92.
C.
Problems
Solve the following problems in the space provided. Show your work.
1. Write the nuclear equations for these processes.
a. the alpha decay of 21884Po

218
84Po
214
82Pb
4
+
2He
b. the beta decay of 21082Pb

210
82Pb
210
83Bi
+
0
-1
2. Complete the following transmutation equations:
a.
9
b.
238
92U
c.
15
4Be
6C
1
+
1H
4
+
+

0n
2He
6
+
3Li
 2 10n +
2He
1
4

240
94Pu
16
6C
3. Write nuclear equations for the following transmutations:
a. the fusion of plutonium-242 and neon-22. One of the two products is four separate neutrons.
242
94Pu
+
22
10Ne

260
104Rf
+ 4 10n
b. the decay of uranium-239. One of the two products is one beta particle.
239
92U

239
93Np
+
-1
0
adapted from Addison-Wesley Chemistry, 1987