Hyde School
Chemistry, Fall 2015
TRIMESTER EXAM REVIEW DAY IV
Nuclear Chemistry
Essential Questions
1. What is the difference between a chemical and a nuclear reaction?
2. Why do elements experience radioactive decay?
3. What are the three different kinds of radioactive particles? What makes each of them distinct?
4. What is a nuclear half-life? How is it calculated?
Part A: Identify the following statements as true or false. If you find that a statement is false, briefly
explain why it is false and/or correct it to be true.
1. A change in the number of protons creates a different isotope.
T or F
2. A change in the number of neutrons creates a different element.
T or F
3. An alpha particle has the same composition as a helium nucleus.
T or F
4. A beta particle has the same composition as an electron.
T or F
5. A radioisotope undergoes nuclear decay to become more stable.
T or F
6. Gamma radiation does not change atomic #, but does change mass #.
7. Alpha decay is a chemical change.
8. Nuclear half-life is an extensive property.
T or F
T or F
T or F
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Part B: Write complete nuclear equations for the following radioactive decay scenarios.
1. Iodine (I)-131 undergoes alpha decay.
2. A parent isotope undergoes beta decay to produce the daughter isotope Bromine-81.
3. Mendelevium (Md)-256 emits two alpha particles.
4. A decay series of Thorium (Th)-232 goes as follows: 2 series of alpha decays and 1 beta decay
and emission of gamma radiation (number your series).
Part C: Solve the following half-life problems using the diagram method (not the nuclear half-life
equation).
1. Actinium-226 has a half-life of 29 hours. If 100 mg of acticinium-226 disintegrates over a period
of 58 hours, what mass of Ac-226 remains?
2. 3 g of Bismuth-218 decay to 0.375 g in one hour. What is the half-life of Bi-218?
3. A sample initially weighs 60 g of Thorium (Th)-234. After 48 days, 7.5 g of Thorium-234
remains. What is the half-life of Th-234?
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4. The half-life of element X is 12 days. If 20 g of element X remain after 72 days, what is the mass
of the original sample?
Part D: Solve the following half-life problems using the nuclear half-life equation.
1. The half-life of Po-218 is three minutes. How much of 2 g sample remains after 15 minutes?
2. Suppose you wanted to buy some of this isotope, and it took 30 minutes to reach you. How much
should you order if you need to use 0.10 g of this material.
3. The half-life of Polonium-218 is 163.7 microseconds. What mass of a 1.0 g sample of Polonium
(Po)-214 remains after 818 seconds?
4. Technetium (Tc)-104 has a half-life of 18 minutes. How much of a 165 g sample remains after
90 minutes?
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