Radioactive Half-Life Lab

Goal: to demonstrate how radioactive materials decay.

Radioactive Half-Life Lab A half-life is the amount of time it takes for half of a radioactive sample to decay through alpha, beta or gamma decay. Radioactive isotopes undergo decay in an effort to become stable or more stable. All isotopes have different half-lives ranging from milliseconds to tens of thousands of years. We will be using sample of radioactive M&Ms to demonstrate how this works. M&Ms that are face down (you cannot see the M) have undergone decay and are stable. M&Ms that are face up (you CAN see the M) are still unstable and therefore radioactive. Materials: M&Ms Paper cup 2 Paper plates Procedure: . Count the # of M&Ms in your cup and record next to Trial 0. Return M&Ms to the cup. 2. Shake the cup and pour the candies out onto the paper plate. 3. Candies with the \"M\" side up represent the undecayed atoms (still radioactive) and the \"M\" side down represent the atoms that have lost their extra energy by radioactive decay. 4. Count the number of undecayed atoms ("M" up) and record as Trial 1. 5. Remove the undecayed atoms (\"M" up) and put them back into the cup. 6 . Transfer the decayed atoms ( "M" down) to the second plate. . Repeat the procedure in steps 2-6, until all of the candies have been removed to the second paper plate, and you have recorded data for several trials. Data Table ( /8pts) BN bR T T S e f0) o] Graph your data: Use the TFaw 001 10 OF ora O ELERE 1 ELTI R T EN (&Y BT Bl (/8pts) Post Lab Questions ( /14pts) You must show work to receive credit 1. If each trial represents one half-life, how many half-lives result in negligible decay (down to 1-2 M&Ms)? 2. Looking at your graph, can recent artifacts be dated accurately using radioactive isotopes? Explain. 3. Would the date accuracy increase or decrease as older and older artifacts are examined? Explain. 4. lodine-131 has a half-life of 8 days. If the mass of iodine-131 is 7 g after 3 days, what was the original mass? . 12.5% of a radioactive sample are left. How many half-lives have passed? Post Lab Questions ( /14pts) You must show work to receive credit 1. If each trial represents one half-life, how many half-lives result in negligible decay (down to 1-2 M&Ms)? 2. Looking at your graph, can recent artifacts be dated accurately using radioactive isotopes? Explain. 3. Would the date accuracy increase or decrease as older and older artifacts are examined? Explain. 4. Todine-131 has a half-life of 8 days. If the mass of iodine-131 is 7 g after days, what was the original mass? /0 of a radioactive sample are left. How many half-lives have passed? 6. How old is an artifact if six half-lives have occurred and the half-live of carbon-14 is 5730 years? 7. If your final mass is 0.01g and the half-life is 15 seconds, what was your starting mass after 60 seconds? Exit: What did the line look like on your graph