Half-life is the time required for something to fall to half its initial value. The half-life of a radioactive element is the time it takes for half of its atoms to decay into something else. M&Ms were chosen because they all have the same m mark on the on one side. In this lab you will go through predicting and counting the number of remaining “mark-side up” candies that should help understand that rates of decay of unstable nuclei and how it can be measured; that the exact time that a certain nucleus will decay cannot be predicted; and that it takes a very large number of nuclei to find the rate of decay. Purpose
To stimulate the transformation of a radioactive isotope with M&Ms over time and to graph the data and relate it to radioactive decay and half-lives.
Materials and Safety
* 200 pieces of M&Ms (trademark only)
* Shoe Box
* Paper Towel
Safety- No safety precautions needed
1. Count out 200 M&Ms. Place all 200 candies in the shoe box with the letter facing up 2. Cover the box and shake it vigorously for 3 sec. This is 1 time interval. 3. Remove the lid and take out any atoms (candies) that have “decayed”, that is, that are now showing lettered sides down. Record on the data table the numbers of decayed and remaining atoms. 4. Replace the cover on the box, and shake for another 3-sec time interval. Record the number of “radioactive’ atoms remaining. 5. Keep repeating time interval trials until all atoms have decayed or you have reached 30 sec on the data table 6. Repeat the whole experiment a second time, and record all data. 7. Average the number of atoms left at each time interval from both trial. Make a graph of your data showing the average number of atoms remaining versus time
1. After how many time intervals (shakes) did one-half life of your atoms (candies) decay? Trial 1- 1 interval Trial 2- 1 interval
2. What is the half-life of your candies?
3. If the half-life model decayed perfectly, how many atoms would be left after 12 sec? 12.5
4. If you increased the amount of atoms (candies), would the overall shape of the graph be altered? Maybe, the amount of M&Ms that are flipped over after shaking is always a gamble and you never know what you’re going to get Graph of the average number of atoms remaining versus time.
8. After one shake, which is one time interval, almost half ouf our atoms decayed. 9. The half life of the cadies is three seconds. 10. If this experiment had been conducted perfectly, 12.5 atoms would be left. 11. No, overall the shape wouldn’t change it would may become a slight rounder or steeper but the dominate shape of the line would not change 12. The experiment did not work perfectly. The percentages came pretty close to 50%. Some were way off, but for the most part they were close to 50%. From 3 to 12 secs was the closet to 50% than the other time intervals. From 18 to 30 secs the percentage started to steer father from 50%. I believe this happened because the less amount of candies or atoms the less chance the atoms will decay.