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Nuclear Chemistry

Nuclear Chemistry. Fact!. A Transmutation is any alteration in the nucleus There are no stable isotopes above element #83 Elements that are unstable will emit energy in the form of Radiation Called Radioisotopes Stability is based on the P:N Ratio. Types of Particles that are Emitted.

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Nuclear Chemistry

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  1. Nuclear Chemistry

  2. Fact! • A Transmutation is any alteration in the nucleus • There are no stable isotopes above element #83 • Elements that are unstable will emit energy in the form of Radiation • Called Radioisotopes • Stability is based on the P:N Ratio

  3. Types of Particles that are Emitted

  4. The Effects of an Electric field on Charged Particles

  5. 2 Types of transmutations A type of Decay that occurs naturally therefore you will see only 1 reacting nuclei that will undergo a change 1. Alpha ( )Decay 2. Beta ( )Decay 3. Positron ( ) emission 4. Gamma ( ) decay A type of Decay that does not occur naturally, therefore you will see 2 nuclei reacting 2 Types 1. Fusion 2. Fission 1. Natural Artificial

  6. Natural Decayand Writing Nuclear Equations Notice several things about it: 1) The atom on the left side is the one that splits into two pieces. 2) One of the two atoms on the right is ALWAYS an alpha particle.3) The other atom on the right ALWAYS goes down by two in the atomic number and four in the mass number. Alpha

  7. More Examples of Alpha decay

  8. Check it and compare the three points to the example. Keep in mind that this equation shows the left-hand side splitting into the two pieces shown on the right-hand side. OK, write the alpha decay equations for these five nuclides. Then click the link to see the answers. Check it and compare the three points to the example. Keep in mind that this equation shows the left-hand side splitting into the two pieces shown on the right-hand side. OK, write the alpha decay equations for these five nuclides. Then click the link to see the answers. More Examples of Alpha decay Check it and compare the three points to the example. Keep in mind that this equation shows the left-hand side splitting into the two pieces shown on the right-hand side. OK, write the alpha decay equations for these five nuclides.

  9. Beta decay and writing equations

  10. Beta decay practice Here's your first set of exercises. Write out the full beta decay equation. Then click the link to see the answers.

  11. Beta decay practice Here's your first set of exercises. Write out the full beta decay equation. Then click the link to see the answers.

  12. Positron emission B+, +1e0 19K37 ------> +1e0 + 18Ar37 Side Note: K Capture (capture and electron) yields the same results -1e0 + 19K37 ------> 18Ar37

  13. Pet scan (positron emission)

  14. Gamma decay No change in Mass or Charge

  15. Artificial DecayThe conversion of matter into energy • A reaction where 2 lite nuclei (alike) are joined together to make a heavier nuclei. • Ex: Reactions on the Sun • Good: Yields A lot of Energy • Bad: Requires a lot of energy to run • Fuse 2 like nuclei (repel) • Need particle accelerators to inc. KE • Synchroton • Cyclotron • The splitting of heavy nuclei (bombard with high energy Neutrons 0N1) into a smaller nuclei • Good: Yields a lot of energy • Bad: Produces a lot of Radioactive waste (disposal issues and half life) Fusion Fission

  16. Fusion 1H1 + 1H1 -----> 1H2 + +1e0 + energy 1H1 + 1H2 -------> 2He3

  17. Fission 0n1 + 92U235 ------> 56Ba142 + 36Kr91 + 3 0n1 + ENERGY 0n1 + 92U235 ------> 54Xe143 + 38Sr90 + 3 0n1 + ENERGY

  18. Half-life The time that it takes for a substance (radioactive) to lose ½ its mass. Determine the Age of rocks (Carbon Dating) During Half-Life Problems Remember: the longer the half-life, the SLOWER the decay (Dangerous) The shorter the half-life, the faster the decay (used in medicine)

  19. Calculating the half-life You will need to know 5 things Total time ½ life time # of half life Initial Mass Final Mass

  20. If asked what fraction remains? • Always start with (1) • If starting with Initial Mass # of Half lifes # of Half lifes 128g 64g 32g 16g 8g 4g 2g 1g 1 1/2 1/4 1/8 1/16 1 2 3 4 5 6 7 1 2 3 4

  21. Half-Life Initial Mass 2 = # # of ½ lifes Total Time ½ life time 2 Final Mass

  22. The half-life of Zn-71 is 2.4 minutes. If one had 100.0 g at the beginning, how many grams would be left after 7.2 minutes has elapsed? 12.5g remaining Os-182 has a half-life of 21.5 hours. How many grams of a 10.0 gram sample would have decayed after exactly three half-lives? 8.75g decayed, 1.25g remain 3) At time zero, there are 10.0 grams of W-187. If the half-life is 23.9 hours, how much will be present at the end of one day? Two days? Seven days? 1 day = 5.00g, 2 days = 2.50g, 7 days = .078g

  23. Uses of radioisotopes • Carbon Dating – C14 no longer taken in by a dead organism • Ratio of U238/Pb206 to date rocks • I131 – used to study thyroid conditions • Co60 – emits large amounts of gamma radiation. Used in treating cancers like Prostate • Co60 and Cs137 – emit gamma rays, used to kill Anthrax Bacilli • Tc43 –used to treat cancerous tumors, absorbed by cancer cells

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