Half-Life Calculations
A 20 g sample of a radioactive isotope has a half-life of 5 years. What mass remains after 5 years?
10 g
Complete the equation:
²²⁶₈₈Ra → ⁴₂He + ____
²²²₈₆Rn
Which emitted particle has a charge of −1?
Beta particle
The spontaneous breakdown of unstable nuclei is called...
Radioactive decay
Carbon-14 dating is used to determine the age of what type of materials?
Once-living things
A sample of radioactive material decays to 30 g after two half-lives. What was the original mass?
120 g
Identify the type of decay shown below:
²³⁸₉₂U → ²³⁴₉₀Th + ⁴₂He
Alpha decay
When an atom of cobalt-60 decays, what type of particle is released?
Beta particle
During radioactive decay, the nucleus becomes more...
Stable
Suggest a reason as to why cobalt-60 used in some cancer treatments.
It emits radiation that can destroy cancer cells.
How much of a 40 g sample of carbon-14 remains after 11,460 years?
10 g
Complete the equation:
¹⁴₆C → ____ + ⁰₋₁e
¹⁴₇N
Which type of radiation has the greatest penetrating ability?
Gamma radiation
Which process combines small nuclei to form a larger nucleus?
Nuclear fusion?
Which type of radiation is most commonly used to sterilize medical equipment because it can penetrate all types of packaging?
Gamma radiation
A radioactive isotope has a half-life of 3 days. How many days are required for a 160 g sample to decay to 20 g?
9 days
Complete the equation:
²⁷₁₃Al + ⁴₂He → ³⁰₁₅P + ____
¹₀n
When an atom of potassium-37 decays, what type of particle is released?
A positron
Which process splits large nuclei into smaller nuclei?
Nuclear fission
Identify one example of a chemical change, and explain how this change differs from a nuclear change.
[Answers vary]
If 12.5% of an original sample of iodine-131 remains, how many days have passed?
24 days
Complete the equation AND determine the type of decay:
²³⁴₉₀Th → 0-₁e + ____
²³⁴₉₁Pa AND beta decay
Compare alpha, beta, and gamma radiation in terms of charge and penetrating ability.
Alpha: +2 charge, least penetrating.
Beta: −1 charge, moderate penetration.
Gamma: no charge, greatest penetration.
Why do nuclear reactions release more energy than chemical reactions?
Nuclear reactions involve changes in the nucleus and convert mass into energy.
State one advantage and one disadvantage of nuclear power.
Advantage: large energy output/low greenhouse gases.
Disadvantage: radioactive waste/risk of accidents.