Lab Investigation: Alpha Decay
Procedure:
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
Go to http://phet.colorado.edu/simulations/sims.php?sim=Alpha_Decay
Click on Run Now.
Click on Single Atom.
Choose a polonium-211 nucleus.
Click on the play arrow.
Question: How long does it take for a single polonium-211 nucleus to decay?
Click on “reset all nuclei.”
Repeat steps 4 and 5 two more times.
Question: Are the results the same each time? Why or why not?
Place your results in the table below.
Trial #
1
2
3
Decay time
11. Repeat the above steps for a “custom” nucleus.
12. Question: how long does it take for a single custom nucleus to decay? Are the results the same
after each simulation?
13. Place your results for the three simulations in the table below:
Trial #
Decay time
1
2
3
14. Click on “multiple atoms”.
15. Click on “reset all”.
16.
17.
18.
19.
Choose a polonium-211 nucleus.
Add 20 atoms to the bucket.
Click on the play arrow.
The half life is marked in red. How many atoms are left after one half life?
20.
21.
22.
23.
How many atoms are left after two half lives?
Repeat the simulation for the custom nucleus.
How many atoms are left after one half life?
How many atoms are left after two half lives?
Analysis
1. Based upon your observations, is the number of atoms that decays after 1 half-life always the
same, or does it appear to be random?
2. From your answer to (1), suggest a way to model radioactive decay using an everyday process
(i.e., on Friday we used the tossing of sugar cubes).