1. Nuclear Chemistry A BRIEF Overview

2. Just the Basics Nuclear chemistry is not a huge focus, but you should be aware of the basics Nuclear chemistry is not a huge focus, but you should be aware of the basics There will be no problem set There will be no problem set BUT…you should review Chapter 23 BUT…you should review Chapter 23 The sections on applications of nuclear chemistry make for very interesting reading The sections on applications of nuclear chemistry make for very interesting reading

3. What Is Radioactivity? Radioactivity - The process by which atoms spontaneously emit high energy particles or rays from their nucleus. Radioactivity - The process by which atoms spontaneously emit high energy particles or rays from their nucleus. First observed by Henri Becquerel in 1896. First observed by Henri Becquerel in 1896.

4. Radioactive elements He Rn Xe I Kr Br Se ArClS NeFO P NC H Li Na Cs Rb K TlHgAuHfLuBa Fr PtIrOsReWTaPoBiPb Be Mg Sr Ca CdAgZrYPdRhRuTcMoNb LrRa ZnCuTiScNiCoFeMnCrV InSbSn GaGe Al At Te As Si B GdTbSmEuNd U PmCe Th Pr Pa YbLaErTmDyHo CmBkPuAmNpNoAcFmMdCfEs RfDbSgBhHsMt110111112

5. Types of Radiation Alpha (  ) Alpha (  ) Nucleus of Helium-4 Nucleus of Helium-4 2+ charge 2+ charge Symbol: or Symbol: or Beta (  ) Beta (  ) Composed of electrons Composed of electrons 1- charge 1- charge Symbol: or Symbol: or Gamma (  ) Gamma (  ) Electromagnetic radiation Electromagnetic radiation No charge or mass No charge or mass Unaffected by EM fields Unaffected by EM fields Highest energy form of radiation Highest energy form of radiation

6. Types of Radioactive Decay Alpha decay Alpha decay Alpha particle is released Alpha particle is released Example Example Beta decay Beta decay Three types: Three types: Electron emission (neutron decays into an electron & a proton; antineutrino also released) Electron emission (neutron decays into an electron & a proton; antineutrino also released) Example Example Positron emission (positron & neutrino are released) Positron emission (positron & neutrino are released) Example Example Electron capture (an electron is captured by the nucleus) Electron capture (an electron is captured by the nucleus) Example Example Gamma decay Gamma decay Results from the emission of a photon of EM radiation Results from the emission of a photon of EM radiation Nucleus of nuclide goes from an excited state to a ground state Nucleus of nuclide goes from an excited state to a ground state

7. Example A patient is given radioactive iodine to test thyroid function. What happens to the iodine? A patient is given radioactive iodine to test thyroid function. What happens to the iodine? Is this equation balanced? Is this equation balanced? You must see if the mass and charge are the same on both sides. You must see if the mass and charge are the same on both sides. 131 53 I Xe +  - +  131 54

8. Example 131 53 I Xe + +  131 54 Mass 53 protons 54 protons 78 neutrons 77 neutrons 131 total mass131 total mass Charge +53, protons+54 charge, protons -1 charge from  - +53 total charge Yes - it’s balanced e 0

9. Why atoms decay Some nuclear arrangements are less stable than others. Some nuclear arrangements are less stable than others. A radioactive isotope decays to form a more stable nucleus. A radioactive isotope decays to form a more stable nucleus. It decays by emitting: It decays by emitting: - mass(alpha particles) - mass(alpha particles) - charge(beta particles) - charge(beta particles) - energy(gamma rays) - energy(gamma rays) There are other ways but these are not seen in nature. There are other ways but these are not seen in nature.

10. Half-life examples Name Half-life Name Half-life Carbon-14 5730 years Carbon-14 5730 years Sodium-24 15 hours Sodium-24 15 hours Iron-59 45 days Iron-59 45 days Cobalt-60 5.3 years Cobalt-60 5.3 years Nickel-63 100 years Nickel-63 100 years Uranium-235 704 million years Uranium-235 704 million years

11. Nuclear power Power can be obtained two ways. Power can be obtained two ways. FissionSplitting atoms FissionSplitting atoms Get energy if the nucleus is big. Get energy if the nucleus is big. The smaller ones are more stable. The smaller ones are more stable. What we do in nuclear reactors. What we do in nuclear reactors. FusionJoining atoms FusionJoining atoms Get energy if the nuclei are small. Get energy if the nuclei are small. The larger one is more stable. The larger one is more stable. This is how the sun works. This is how the sun works.

12. Nuclear Fission

13. Chain reaction

14. Shielding and types of radiation Alpha particles Alpha particles Blocked by 1 cm of air. Blocked by 1 cm of air. Beta particles Beta particles Requires 1 mm of aluminum to block. Requires 1 mm of aluminum to block. Gamma rays Gamma rays Most penetrating. Need concrete or lead to provide adequate protection. Most penetrating. Need concrete or lead to provide adequate protection. X-rays X-rays The same as gamma rays. The same as gamma rays.

15. Uses of radionuclides Our ability to measure radioactivity is very sensitive. As a result, radioisotopes have a number of uses. Our ability to measure radioactivity is very sensitive. As a result, radioisotopes have a number of uses. In addition, its interaction with living matter can also be exploited. In addition, its interaction with living matter can also be exploited. Uses includes Uses includes Dating techniques Dating techniques Cancer treatment Cancer treatment Tracers Tracers Imaging Imaging Testing methods Testing methods

16. Carbon dating Carbon-14 is constantly being produced in the upper atmosphere by cosmic rays at an almost constant rate. Carbon-14 is constantly being produced in the upper atmosphere by cosmic rays at an almost constant rate. N + n C + H N + n C + H It rapidly combines with oxygen in the air to make CO 2. It rapidly combines with oxygen in the air to make CO 2. 14 C + O 2 14 CO 2 14 7 1010 14 6 1111

17. Carbon dating After death, the carbon-14 decays with a half-life of 5730 years. After death, the carbon-14 decays with a half-life of 5730 years. We can tell how old things are based on the amount of carbon-14 that remains. We can tell how old things are based on the amount of carbon-14 that remains. The method is pretty good in the 1,000-20,000 year range. The method is pretty good in the 1,000-20,000 year range. Ideal tool for dating the artifacts of man - or at least it was. Materials like plastics are 14 C depleted. Ideal tool for dating the artifacts of man - or at least it was. Materials like plastics are 14 C depleted.

18. Medical applications Cancer therapy Cancer therapy Radiation both causes and can treat cancer Radiation both causes and can treat cancer Radiation causes molecules in the cell to break apart - ionization Radiation causes molecules in the cell to break apart - ionization Most significant damage is when DNA is destroyed. Most significant damage is when DNA is destroyed. Effect is greatest in rapidly growing cells. Effect is greatest in rapidly growing cells.

19. Examples of radiation treatment External bombardment External bombardment 60 Co- expose area to gamma rays. 60 Co- expose area to gamma rays. Implants Implants 182 Ta- used as wire, treatment of eye. 182 Ta- used as wire, treatment of eye. 137 Cs- use in a balloon catheter for bladder. 137 Cs- use in a balloon catheter for bladder. Interstitial therapy Interstitial therapy 198 Au- inject directly into tumor. 198 Au- inject directly into tumor. Internal irradiation Internal irradiation 131 I- Ingest solution, goes to thyroid. 131 I- Ingest solution, goes to thyroid.

20. Nuclear tracers Our ability to measure radiation is VERY sensitive. Our ability to measure radiation is VERY sensitive. Can introduce a small amount of a radioactive material and see where it goes in the body or even within a cell culture - Tracers Can introduce a small amount of a radioactive material and see where it goes in the body or even within a cell culture - Tracers Can be used to measure small amounts of chemicals in the body like hormones - Radioimmunoassay Can be used to measure small amounts of chemicals in the body like hormones - Radioimmunoassay