21.1
Lab Activity
Nuclear Chemistry
North High
Chemistry
Name
Hour
Radioactive Decay of Candium
How long will it take for a sample of Eminemium to completely transmutate into a new element?
Procedure:
1. Count and record the total number of m&m’s that you start with.
2. Place all the atoms of Eminemium into the cup.
3. Record your “Start time” to the nearest minute.
4. Cover the cup and gently shake for a few (3-7) seconds.
5. Gently pour out the candy onto a plate or onto a sheet of paper.
6. Count the number of pieces with the print side up and record the number in 1) “Number of
Undecayed Atoms.”
7. Return the “Undecayed Atoms” to the cup.
8. Count the number of pieces with the print side down and record the number in 1) “Number of
Decayed Atoms.”
9. Consume or stash the “decayed” atoms.
10. Gently shake the cup again for a few seconds.
11. Repeat steps 5-9 for Half-life.
12. Continue shaking, counting and consuming until all of the atoms have decayed.
13. Record your “End time” to the nearest minute.
14. Determine the “Average half-life in seconds” by finding the change in end time vs. start time
in minutes and then multiply your answer by 60 to convert to “Total time in seconds”. Record
your answer. Next, divide the “Total time in seconds” by the total number of Half-lives to find
the “Average half-life” and record it.
15. Use the data to graph of the Number of Undecayed Atoms vs. Total Time in Seconds on the
backside of this lab sheet.
Data:

Total number of m&m’s your group started with __________ (1st point on graph)


Start time in minutes _________ End time in minutes __________
Change in time (end - start time) in minutes = ________ X 60 = __________Total time in sec.

Total time in sec. _______
Half-life
1)
2)
3)
4)
5)
6)
7)
8)
9)
10)
11)
12)
/ Total number of half-lives = ________ Average half-life in sec.
Number of Undecayed Atoms
Number of Decayed Atoms
Graph of the Number of Undecayed Atoms vs. Total Time
150
140
130
120
110
90
80
70
60
50
40
30
20
10
0
Number m&m’s
started with
Number of Undecayed Atoms
100
1st ½ life
TOTAL
TIME
2nd ½ life
TOTAL
TIME
3rd ½ life
TOTAL
TIME
4th ½ life
TOTAL
TIME
5th ½ life
TOTAL
TIME
6th ½ life
TOTAL
TIME
7th ½ life
TOTAL
TIME
8th ½ life
TOTAL
TIME
9th ½ life
TOTAL
TIME
______
______
______
______
______
______
______
______
______
Total Time (sec.)
Questions:
1. How would a longer half-life affect the shape of the graph?
2. Using the graph, how many m&m’s would you have at 4 ½ half-lives? ____________
3. If you had started with twice as many m&m’s, how many more half-lives would it have
taken, on average, for your “sample” to totally decay? ____________
4. If you have four times as much radioactive material with a half-life of 10 years, how many,
on average, more years would it take to totally decay? ____________
5. If you had one million “Skittlium” with a half-life of 100 seconds, how long would it take
to completely decay? ____________
6. Considering the average length of Eminemium’s half-life, would you consider it a long or
short half-life ____________ and what are the advantages and disadvantages?