Nuclear Decay

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Nuclear Decay

  1. 1. Name ______________________ Date _______________________ Nuclear Chemistry: Identifying Forms of Radiation Nuclear reactions are quite different than chemical reactions in that they involve a change inside the nucleus rather than an exchange or sharing of electrons. An unstable nucleus decays into a products that are more stable. When an unstable nucleus decays, it releases radiation in the form of alpha particles, beta particles, and/or positrons. 239 235 4 Alpha Decay: Pu U + He 94 92 2 60 60 0 Beta Decay: Co Ni + β 27 28 −1 37 37 0 Positron Emission: Ca K + β 20 19 +1 Directions: Place a check to identify the form of radiation demonstrated by each reaction below. Alpha Beta Positron 1. 234 234 0 Pa U + β 91 92 −1 2. 222 218 4 Rn Po + He 86 84 2 3. 37 37 0 K Ar + β 19 18 +1 4. 99 99 0 Tc Ru + β 43 44 −1 5. 19 19 0 Ne F + β 10 9 +1 6. 32 32 0 P S + β 15 16 −1 7. 238 234 4 U Th + He 92 90 2 8. 53 53 0 Fe Mn + β 26 25 +1 9. 220 216 4 Fr At + He 87 85 2 © 2003 Teachnology, Inc. 15
  2. 2. Name ______________________ Date _______________________ Nuclear Chemistry: Predicting Nuclear Decay Part 1 Directions: Predict the products of the following nuclear reactions. 235 231 1. U Th + ________________ 6 1 4 2. Li + n He + ________________ 3 0 2 14 14 3. C N + ________________ 6 7 226 222 4. Ra Rn + ________________ 32 0 5. P + e ________________ −1 220 4 6. Fr + He ________________ 87 2 198 198 7. Au Hg + ________________ 14 4 1 8. N + He H + ________________ 7 2 1 © 2003 Teachnology, Inc. 16
  3. 3. Name ______________________ Date _______________________ Nuclear Chemistry: Predicting Nuclear Decay Part 2 Directions: Predict the reactants of the following nuclear reactions. 231 4 1. ________________ Th + He 2 0 131 2. ________________ e + Xe −1 54 4 241 1 3. ________________ + He Pu + n 2 0 0 10 4. ________________ e + B −1 5 7 8 5. Li + ________________ Be 4 235 72 1 160 6. U + ________________ Zn + 4 n + Sm 0 62 0 3 7. ________________ e + He −1 216 4 8. ________________ At + He 85 2 © 2003 Teachnology, Inc. 17
  4. 4. Name ______________________ Date _______________________ Nuclear Chemistry: Half-life Radioactive substances decay at a constant rate. There are a number of unstable nuclei that decay in a given time. The time that it takes for half of the atoms in a given sample of an element to decay is termed the half-life. To determine half-life: To determine how much of an unstable remains after a given time: Half-life = total time elapsed half-life Fraction remaining= (1/2)Half-life Data Table 1: Known Half-life of selected elements: 198 131 42 Au: 2.69 days I: 8.07 days K: 12.4 hours 32 90 53 P: 14.3 days Sr: 28.1 years Fe: 8.51 minutes 1. Predict the mass of a 75.00 g sample of 198Au after 16.14 years. 2. How many days are required for 32P to undergo 6 half-lives? 3. Predict the mass of a 125.00 g sample of 42K after 62.0 years. 4. Of all of the elements listed above, which element decays the fastest? Predict the mass of a 107g sample of this element after 34.04 minutes. 5. If a 120 g sample of a radioactive element decays to 15 g in 40 minutes, what is the element’s half-life? © 2003 Teachnology, Inc. 18
  5. 5. Name ______________________ Date _______________________ Nuclear Chemistry Review Quiz: Form A Directions (Questions 1 and 2): For questions 1 and 2 predict the missing reactant or product and identify the form of radiation demonstrated in each problem. 198 198 1. Au Hg + ________________ Form of radiation: __________________ 238 241 1 2. U + ________________ Pu + n 0 Form of radiation: __________________ 85 3. Predict the mass of a 135 gram sample Kr after 32.28 years. 85 Kr Half-life = 10.76 years ---------------------------------------------------------------------------------------------------------- Nuclear Chemistry Review Quiz: Form B Directions (Questions 1 and 2): For questions 1 and 2 predict the missing reactant or product and identify the form of radiation demonstrated in each problem. 14 14 1. C N + ________________ 6 7 Form of radiation: __________________ 0 3 2. ________________ e + He −1 Form of radiation: __________________ 32 3. Predict the mass of a 155 gram sample P after 28.6 days. 32 P Half-life = 14.3 days © 2003 Teachnology, Inc. 19

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