Radioactive Decay of M & M’s

Radioactivity is the spontaneous decay of nuclei. The half-life is the time it takes for half of a radioactive nuclei to decay (or breakdown). Today we are going to show this process with M & M’s. We will record our results in a table, and graph the results.


Paper towel Cup M & M’s


1.  Clean desk with cleaner.

2.  Sanitize hands.

3.  Place clean paper towel on desk with cup.

4.  Place bag of M & M’s on balance to determine the mass of the M&M’s. Record your answer.

5.  Open bag of M&M’s. Pour onto to paper towel. Count the total number of M&M’s. Record your answer.

6.  Sort the M&M’s by color. In a table, record the color and number of each color into a table similar to the one at the bottom of the page.

7.  Pour M&M’s in a cup. Shake M&M's up; pour them onto the paper towel. If the “M” is up, it has decayed. Record the number of M&M’s that decay during each “half-life” into a table similar to the one below. Each half-life is represented by a shake and pour of the M&M’s. Eat the M&M’s that have decayed. Pour remaining M&M’s back into the cup.

8.  Repeat procedure until no M&M’s remain.


1.  Determine the average mass of one M&M by divided the total number of M&M’s by the mass of the bag of M&M’s. Record your answer in grams. Example: 54 M&M’s/ 45.2 g = 1.19 grams for each M&M.

2.  Determine the percentages for each color in the bag by using Part/Whole x 100 = %. The Part (which represents each color) divided by Whole (which represents the total number of M&M’s) times 100 equals the percentage. Example: 10/50 x 100 = 20%.

3.  In a circle graph, graph the percentages of each color in the bag.

4.  Graph the results from the decay of M&M’s into a bar graph. Graph the number of half-lives on the x-axis and M&M’s that decayed on the y-axis.

5.  If the M&M’s were placed on a shelf 2 meters high, what would their potential energy be? Remember the equation to solve for Potential Energy is PE = mgh where m is the mass, g is acceleration due to gravity (9.8 m/s2), and h is the height in meters above the Earth’s surface. Don’t forget that energy is measured in Joules.


1.  Mass of bag of M&M’s ______grams.

2.  Total number of M&M’s ______.

3.  Average mass of one M&M ______grams.

4.  PE = ______Joules.

Color of M&M’s / Number of color / Percentage of M&M’s
Number of half-lives / Number of M&M’s that decayed