# Radioactive dating lab pennies

Any pennies that land tails up are assumed to have "radioactively decayed" on this toss.

Stack the tails-up pennies into a column on the far side of the table.

Tupperware container (with top)*, 100 pennies, plastic cup, graph paper (one per student), rulers, handout (attached, one for each student), Periodic Table, tables of isotopic decay types and half-lives*I have found it works well to identify the isotope with a post-it on the top of each groups Tupperware container. These pennies represent those that have undergone radioactive decay. Count the heads up pennies that remain in the original container and record the number in the data table. Repeat steps 1-3 with the remaining pennies for 3 additional half-life periods.

Common isotopes to use are carbon-14, iodine-131, cobalt-60, hydrogen-3, strontium-90, and uranium-238, though any radioactive isotope with a known decay type and half-life can be used. Data: Data Analysis: On the graph paper provided, graph mass vs. Plot all points then connect them with line of best fit. Conclusions: 1) Write the nuclear decay equation for the radioisotope that you were given.

It's best if you actually do this experiment "live" (tossing pennies is fun! However, if you don't have 100 pennies handy, you can use this coin decayer application . Once you have completed the data-taking, look at your columns of pennies. To get an even more detailed look at the shape, you might think about how to combine the data for your group with the data from other groups.

If you didn't use the coin decayer application, you should draw a graph that represents the number of pennies in each column vs. Repeat the entire experimental procedure again and draw a new graph for the height of the pennies. Now try finding which function best approximates the shape you see.

The amazing thing is that we can accurately mimic, in a quantitative way, what happens during radioactive decay with just a few pennies. Well, start by noting that when you toss a single coin, the chance that it will land tails up is about 50%, the same as the chance that it will land heads up. If you toss a bunch of pennies into the air, the chance that any particular one of them will be tails up is still 50%.

If a particular penny lands heads up on the first toss, the chance that it will land tails up on the second toss is still 50%.

This function is useful for describing many very different observations in science.Your equation should show the number of pennies that will decay for any particular toss.Remember, we assume that the number of decays depends only on the number of pennies we have just before each toss. Now try to find the values of the variables that give the best "fits" to your data for the pennies.What do you predict the curve for an experiment of 100 dice would look like?What would you expect for the theoretical curve that fits the data taken in the experiment? Not every group needs to assume that one dot facing up indicates decay.

In this experiment, you will consider a similar case, that of radioactive decay. If the material is radioactive, that means that some of its atoms are continually dying, or, more accurately, they are being transformed into some other type of atom.