Nuclear Physics Practice Test
Name: _______________________
Date: ___________ Period: _____
I. VOCABULARY
Each sentence is false; correct each sentence by changing only the underlined words.
1. The atomic number counts the number of neutrons while the neutron number counts the nucleons.
2. The nuclear force tries to pull the nucleus apart, but the gravitational force holds it together.
3. The nuclear force only acts over very long distances. This explains why heavy nuclei are stable.
4. When a nucleus is stable, it will release energy until it becomes stable.
5. Beta rays are helium nuclei, alpha rays are electrons, and delta rays are photons.
II. NUCLIDES
6. Write the symbol and then draw a picture of each of the following nuclides.
(a) Helium-4
(b) Boron-12
(c) Lithium-7
(d) Hydrogen-2
III. CULMINATING PROBLEM
7. Hydrogen-3 known as tritium is radioactive and is an important component in the making of nuclear
weapons. It decays through beta emission with a half-life of approximately 12 years.
(a) Draw a picture of the decay of tritium and
then write the name of the daughter nucleus.
→
(b) What type of radiation is released when
tritium decays?
(c) Write the decay equation for tritium.
Hydrogen-3
Suppose the United States nuclear weapons arsenal currently contains approximately 80 kg of tritium.
(d) In order to maintain its current nuclear
weapons arsenal, how much tritium must the
US produce every 12 years?
Fremont Physics ©Kepple 2013
Nuclear Physics – Page #9
(e) If the US were to stop replenishing its stocks
of tritium, how many years would it take until
there were only 5 kg of tritium left?
Nuclear Physics Study Guide
MAJOR CONCEPTS
The electric force is a long-range force that
exists between charged particles. Since protons
repel, this force pulls the nucleus apart.
The nuclear force is a short-range force that
exists between nucleons. Since nucleons
attract, this force holds the nucleus together.
The strength of the electric force is determined
by the atomic number (number of protons).
The strength of the nuclear force is determined
by the mass number (number of nucleons).
If the electric force or nuclear force is too
powerful, the nucleus will be radioactive, which
means it will decay and release radiation.
All elements with more than 82 protons are
radioactive since there are so many protons,
the nuclear force cannot stabilize the nucleus.
VOCABULARY
atomic number (Z) – number of protons
neutron number (N) – number of neutrons
mass number (A) – number of nucleons
NUCLIDES
To refer to a nuclide, we need only give the
atomic number and the mass number. There
are two ways to do this:
isotope: various forms of the same element that
contain an equal number of protons but different
numbers of neutrons in their nuclei.
mass
number
atomic
number
symbol
6
3
name
Li
Lithium-6
element
name
mass
number
NUCLEAR DECAY SCHEMES
Alpha decay occurs when the nucleus has too
many protons. As a result, the electric force
dominates and a helium-4 nucleus is emitted.
Beta decay occurs when the nucleus has too
many neutrons. As a result, the nuclear force
dominates and a neutron turns into a proton.
→
→
HALF-LIFE
The half-life is the time it takes for
half of a sample of a radioactive
isotope to decay.
Half-life is a measure of instability.
The more unstable a nucleus, the
shorter its half-life will be.
0 half-lives
100%
1 half-life
50%
2 half-lives
25%
3 half-lives
12.5%
1
1
1
2
1
4
1
8