A Radioactive Half-Life Lab Activity
Radioactive half-life is the time it takes for one-half of the atoms of a radioactive substance to decay into it’s daughter element. Each radioactive element has it’s own half-life, ranging from fractions of a second (as with the heavier synthetic elements) to billions of years, as with Uranium-238. In this lab activity, you will simulate radioactive decay using pennies.
1. On a piece of graph paper, create a graph that will plot:
# of radioactiveatoms remaining (heads) vs. time (in seconds)
3. a. After 2 half-lives, how many radioactive pennies (heads) were left? ______
4. How many radioactive half-lives will it take to reduce the radioactivity to about 12% of the original amount?
5. Can you predict which penny in your jar will decay? Explain why or why not.
6. How does this graph model radioactive decay of any radioactive element?
Use the chart below, answer the following questions.
2. Nuclear waste dumped at Hanford Nuclear Depository in Eastern Washington is mostly Plutonium-239. If government regulations state that 10 half-lives must pass before the waste is safe for exposure to humans, how many years must pass before the waste can be released safely?
3. Why does Iodine-131 make a good radioactive element to use as tracer in medical tests?
4. Dating fossils is found by determining the percentage of radioactive Carbon-14 atoms that remain in the bones. If the percentage of the Carbon-14 atoms is 25% of normal, roughly, how old might the fossils be (in years)?
5. Do radioactive elements remain radioactive forever? Explain.