Solve problems involving radioactive decay rates

1. Objective Solve problems involving radioactive decay rates

2. O.A # 16 Radioisotope

3. Chapter 25 Nuclear Chemistry

4. Radiation and Mutation file:///C:\Users\garcia_li\Desktop\MyOpinionsJournal.pdf

5. Transmutation Transmutation is where an element is converted into another element by the spontaneous emission of radiation Except for gamma radiation, all nuclear reactions are transmutation reactions. Transmutation can occur naturally, be forced, or induced. Radioactive decays are measured in half-lives

6. Half-life Half-life is the time required for one-half of a radioisotope’s nuclei decay into its products. Equation for half-life Amount remaining = (Initial amount) (½)n n= number of half-lives Practice Problems pg. 819 # 17 17) Gallium-68 10.0 mg Gallium-68 1 half-life 5.00 mg (68.3 min) 2 half-lives 2.50 mg 136.6 min 3 half-lives 1.25 mg 204.9 min

7. Amount remaining = (Initial amount) (½)n 18)25.0 mg = (Initial amount) (½)5 25.0 mg = (Initial amount) (1/32) 25.0 mg = (Initial amount) 32 Initial amount = 800 mg

8. 19) polonium-214, 1.0 gram half-life: 163.7microseconds(ųs), in 818 ųs, how many half-lives have passed? Amount remaining = (Initial amount) (½)n 818 = 5 163.7 Amount remaining = (1.0 g) (½)5 Amount remaining = 0.031 grams

9. Half life practice problems Pg. 837 # 77-80

10. Objective • Use pennies to model the half-life of a typical radioactive isotope. Students will collect data, compare and contrast making and using graphs, & apply concepts.

11. O.A # 17 Carbon-14 has a half-life of 5730 years and is used to date archaeological objects. Fresh charcoal made from a tree contains carbon-14 which will give a radioactive count of 13.60 disintegrations per minute per gramof carbon.Prehistoric cave paintings were found in Spain. A piece of charcoal found in the ancient cave in Altamira, Spain gave 1.70 disintegrations per minute per gram of carbon. From this information, determine the age of the cave paintings. http://www.youtube.com/watch?v=81dWTeregEA(Carbon-14 half-life -1min.)

12. O.A # 17 How many half-lives if the initial amount is 13.60 g and the amount remaining is 1.70 g? 3 half-lives have elapsed since the paintings were done. Since the half-life of carbon-14 is 5730years, about how old are the paintings? about 5730 x 3 = 17,190 years old

13. MiniLAB pg. 819Decay Results

14. Modeling Radioactive Decay . Number of Pennies (tails-up pennies) 0 10 20 30 40 50 60 70 80 90 100 0 1 2 3 4 5 6 7 Trial number

15. MiniLAB pg. 819Modeling Radioactive Decay . . . Number of Pennies (tails-up pennies) 0 10 20 30 40 50 60 70 80 90 100 . . . . . . 0 1 2 3 4 5 6 7 8 Trial number

16. Analysis Questions • Graph • . • . • . Summary: (3-4 sentences) I learned….

17. Analysis Questions (anwers) Graph It took approximately one trial for 50% of the sample to decay, 2 trials for 75%, 4 trials for 90% to decay. The half-life is 1 minute. Approximately one-sixth of the dice will decay with each toss.

18. Nuclear chemistry video clips • http://www.youtube.com/watch?v=jk6Hm1QoDYY (Nuclear fusion and fission -5min.)

19. 25.4 Fission and Fusion of Atomic Nuclei Nuclear Fission nuclear fission is the splitting of the nucleus into fragments

20. Chain Reaction A chain reaction is a series of fissions in which the release of neutrons from the splitting of one atom leads to the splitting of others

21. Nuclear Fusion nuclear fusion is the combining of atomic nuclei to form a heavier nucleus (EX: The Sun is powered by a series of fusion reactions as hydrogen atoms fuse to form helium atoms)