NUCLEAR CHEMISTRY UNIT
Introduction to Radiation
Certain types of atoms are unstable or “radioactive” and decay into other atoms by emitting parts
of their nuclei. The speed with which they decay and release radioactive particles or energy is
described by the “half-life”. The “half-life” is defined as the time necessary for half of the atoms
in a sample to undergo radioactive decay and change to another atom by releasing particles. This
“half-life” is not affected by temperature, pressure, or concentration.
Prelab Questions:
1. What are the three types of radioactive particles? Give both the name and the symbol for
each.
2. Nuclear equations can be balanced in a manner similar to chemical equations. In chemical
equations, each side of the equation must have the same number of each type of atom. In
nuclear equations, each side of the equation must have the same mass and the same nuclear
charge. In nuclear equations, you don't need to worry about electrons—after all, electrons are
located outside the nucleus. We balance nuclear equations by summing the mass number and
the nuclear charge. Recall that an atomic symbol is written as shown below.
mass number  13
nuclear charge  6
C
Using this information, balance the following equations. Remember, two requirements must
be met:
1) The sum of mass numbers must be the same on each side of the equation.
2) The sum of nuclear charges must be the same on each side of the equation.
(a)
1
1
0 n1 ____  _____
U  231
91 Pa  ____
(b)
231
92
(c)
6
3
(d)
239
92
(e)
121
51
Li  01n 24 He  _____
U  10 e  _____
Sb  01n  122
51 Sb  _____
Exps. 35 Page
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3. You will be using radiation sources that produce alpha, beta, or gamma rays in their decay
process. Write a balanced the equations below for each of these reactions below.
a) The production of alpha particles by the decay of Polonium-210.
b) The production of beta particles by the decay of Strontium-90.
c) The production of gamma rays and beta particles by the decay of Co-60.
4. What are some ways that you can think of to reduce exposure to radiation?
Exps. 35 Page
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RADIATION INFORMATION SHEET
Radioactivity in Our Lives
1. Smoke detectors: Smoke detectors contain the radioactive element Americium. In a fire, smoke particles
shield the radiation from hitting a detector which causes the alarm to sound.
2. Nuclear energy: The energy produced by the decay of 1 gram of a radioactive substance is over a
million time greater than the energy obtained by burning 1 gram of coal.
3. Carbon dating: The age of ancient relics can be estimated by measuring the amount of radioactive
carbon in the relics.
4. Food Irradiation: "Zapping" or food with radiation (basically giving the food a powerful X-ray) kills
dangerous viruses and bacteria (such as the e-coli virus). This is being considered as a method to make
foods safer.
5. X-rays: X-ray energy is shielded better by bone than by tissue. By putting a piece of x-ray sensitive film
behind a person, an image of a persons bones can be produced.
6. Medical Diagnostics: For certain medical procedures, people are fed (or injected with) a "radioactive
cocktail." The cocktail can be designed to target a specific organ and help doctors diagnose medical
problems.
7. Scientific investigation: Radiation is one of many tools that astronomers, biologists, biochemists,
chemists, geologists, and physicists use to advancing scientific discoveries.
8. Weapons: Nuclear weapons along with chemical weapons (a.k.a. nerve gases) are probably the most
destructive and nondiscriminate weapons available today.
Human Exposure to Radiation
(from M. S. Silberberg. Chemistry: The Molecular Nature of Matter and Change, McGraw Hill: Boston, 2000, p. 1062.)
Natural Sources
The Sun
The Earth
ground (clay/soil)
wooden houses
brick houses
concrete houses
Air (mainly radon)
outdoor
in wooden houses
in brick houses
in concrete houses
Food and water
Exposure (mrem/year)
30-50
25-170
10-20
60-70
60-160
20
70
130
260
40
Artificial Sources
Diagnostic X-rays
Lung
Kidney
Dental
Therapeutic Radiation
Other Sources
Jet flight (4 hrs)
nuclear testing
nuclear power industry
Total Average Value
Exposure (per Dose)
0.04-.2 mrad/film
1.5-3 rad/film
<1 rad
locally  10,000 rad
1 mrem
<4 mrem/yr
<1 mrem/yr
100-200 mrem/yr
Effects of Radiation on Adults
(from M. S. Silberberg. Chemistry: The Molecular Nature of Matter and Change, McGraw Hill: Boston, 2000, p. 1063.)
Dose (rem)
5-20
20-100
50+
100-200
300+
500
400-1000
3000+
Effect
Possible damage to chromosomes
Temporary reduction in white blood cell count
Temporary sterility in men
Vomiting, diarrhea, tiredness
Permanent sterility in women
Bone marrow and intestine destruction
Acute illness, early deaths
Acute illness
Lethal Dose
non lethal
non lethal
non lethal
non lethal
non lethal
lethal to 50-70% pop. (30 days)
lethal to 60-95 % pop. (30 days)
lethal to 100% pop. (2 days)
Exps. 35 Page
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