Radiometric Dating Lab:

Purpose:
• To define the terms half-life and radioactive decay
• To model the rate of radioactive decay
• To create line graphs from collected data
• To compare data
• To understand how radioactive decay is used to date archaeological artifacts

Materials:

• 50 M&Ms

• Graphing app: Desmos Go to: https://www.desmos.com

• Zip Lock Bags (containing M&Ms)

• Pen, Marker, Pencil

• Data Collection Table

• Ipads/Notability Safety:

  Don’t eat the M&Ms!

  Each table has the radioactive element: M&Mnium.
  Your task is to explain the concept of half-life of M&Mnium through radiometric dating. Each group will turn in their own individual lab report to Canvas.

  Procedure:
  • Put 50 M&M’s® candies of any color into a zip lock bag. Each group is starting with 50

  M&M’s® candies, which is recorded as Trial 0 in the data table. All of the

  M&M’s® candies are considered to be radioactive at the beginning.
  • Shake the bag and spill out the candies onto a flat surface.
  • Pick up ONLY the candies with the “m” showing – these are still radioactive. Count the

  “m” candies as you return them to the bag.
  • Record the number of candies you returned to the bag under the next Trial.
  • Move the candies that are blank on the top to the side – these have now decayed to a

  stable state.
  • Repeat steps 2 through 5 until all the candies have decayed or until you have

  completed Trial 7.
  • Record the results for 7 other groups and total all the Trials for the 400 candies.

  Example Data Table:

  The X-axis represents the number of half-lives. The Y-axis represents the number of radioactive M&MNiums remaining after each half-life. If you use the example data table below, you will get a steeply dipping graph. However, in order to visually see the

radioactive decay of M&Mnium on the graph, multiple each of the trials (your X values) by 50. Please see data table 2 for an example of this with an accompanied graph.
Below is an example of what your table will look like for your trials. Your Y values will be different based on your group’s experiment.

X= Number of Half-Lives
Y= radioactive M&Mnium remaining after each trial

Example Graph and Data:

Looking above, you can see that the X values have changed, resulting in a graph that shows the half-life in a more interpretable manner. Your Y variables will be different since they are based on the class’s trials totaled.

Lab Report: Submit this to Canvas below:
What you must turn in is a short (1 page) report explaining your process, showing your graph and data table and a photo of your group performing at least one of the trialsalong with answering the following questions:

1. Why would you perform this 7 times? What would your results look like if you made the graph after one time only?
2. If you had 10,000 M&M’s and went through 5 half lives, how many M&M’s would be "undecayed"? (You can use Desmos and make a data table/graph this if it helps!)

3. If you had 10 M&Ms left after 4 half lives, how much did you originally have?