``` Half-Life Data Worksheet Name: Date: Follow the directions and answer the questions. The following image shows how uranium-238 (a radioactive element) decays and changes to a stable element (lead-206). The half-life of each element is shown in years and days. 1. Hypothesize what half-life is: The Uranium-238 Decay Chain Atomic Number 83 84 85 86 87 8 Only main decays are shown Gamma emitters are not indicated Pb-214 26.8 m a Po-218 3.05 m P Pb-210 22.3 a s Bi-214 19.9 m N a P Po - 214 -4 1.64*10 S p ^ Bi-210 5.0 d \, P Pb-206 Stable a Po-210 138.4 d 89 90 91 92 Th-234 a U-238 24.1 d 4.5x109a P Pa-234 1.17m N, P a Th-230 a U-234 7.7x104a 24x105a Element Names U - uranium Th - thorium Ra - radium Pa - protactinium Rn - radon Po - polonium Bi - bismuth Pb - lead Half-life units a - years d - days h - hours m - minutes s- seconds Observe the half-life demonstration as directed by your teacher. 2. Calculate the number of radioactive atoms remaining after each half-life. Write the number of atoms in the "Number of Radioactive Atoms" column. Plot the number of radioactive atoms on the graph provided. Note that the number of unstable (radioactive) atoms decreases as they are being transformed into stable atoms. Half-Life Number of Number Radioactive Atoms 0 1024 1 2 3 4 5 6 7 8 9 10 1000 900 >s\ | 800 * 700 > '5 600 ra o *5 500 ra cc ¦g 400 ii 300 E = 200 100 0 0123456789 10 Half-Life Number ^ rnA United States _ RadTown Radioactive Atom Activity Set EPA 402-B-19-025 JbNWl Environmental Protection ' * * Agency https://www.EPA.gov/RadTown/Activity-5-Half-Life ``````------- 3. If you had a sample of 4,000 radioactive atoms, how many atoms would remain after 5 half-lives? Half-Life Number Number of Radioactive Atoms 0 4000 1 2 3 4 5 4. If you had a sample of 210 atoms, and you started with a sample of 3,360 atoms, how many half- lives have elapsed? 5. If the half-life of the sample from question 2 is 30 minutes, how many hours did it take to decay from 3,360 atoms to 210 atoms? 6. Can you determine the age of something (like a fossil) by examining its half-life? Explain. 7. In what other ways might it be useful to know a sample's half-life? ^pp/v Environmental Protection RaclTown Radioactive Atom Activity Set EPA 402-B-19-025 * * Agency https://www.EPA.gov/RadTown/Activity-5-Half-Life ````------- `