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Topics for Today

Topics for Today. Nuclear Fission The BIG difference between U-235 and U-238 The Making of the Atomic Bomb Nuclear Power Plants and Breeder Reactors. Readings for Today. What do neutron sources have to do with the atomic bomb? See Section 7.2 Nuclear Waste. Section 7.9.

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Topics for Today

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  1. Topics for Today • Nuclear Fission • The BIG difference between U-235 and U-238 • The Making of the Atomic Bomb • Nuclear Power Plants and Breeder Reactors

  2. Readings for Today • What do neutron sources have to do with the atomic bomb? See Section 7.2 • Nuclear Waste. Section 7.9 What is a breeder reactor? Section 7.6

  3. Topics for Wednesday • Ionizing Radiation and Human Health • The 1st wartime atomic bomb • Cell Damage • Radiation Sickness

  4. Readings for Wednesday • Hazards Associated with Radioactivity Section 7.8 • The DNA double Helix Section12.2

  5. Announcements

  6. Lab this week • Need an alternate lab because of a health concern? • You should have already talked with your TA.

  7. Topics for Today • Nuclear Fission • The BIG difference between U-235 and U-238 • The Making of the Atomic Bomb • Nuclear Power Plants and Breeder Reactors

  8. What does it mean for an isotope to be fissile, or “fissionable?”

  9. Nuclear Fission: The splitting of larger atoms into smaller ones Page 313

  10. Review – Neutron Activation Neutron Activation Equation… Ag + n Ag 109 47 110 47 1 0 Ag + n Ag 107 47 108 47 1 0

  11. Review – Neutron Activation Is this fission? Neutron Activation Equation… Ag + n Ag 109 47 110 47 1 0 Ag + n Ag 107 47 108 47 1 0

  12. Review – Neutron Activation Neutron Activation Equation… Ag + n Ag 109 47 110 47 1 0 How is this different from nuclear fission? How is this similar to nuclear fission?

  13. Review – Neutron Activation You will see this first-hand in lab this week!! Neutron Activation Equation… Ag + n Ag 109 47 110 47 1 0 Ag + n Ag 107 47 108 47 1 0

  14. That was silver… what if we start bombarding uranium with neutrons?

  15. That was silver… what if we start bombarding uranium with neutrons? Then what happens? It depends

  16. Uranium Isotopes U-234 trace U-235 0.72% U-238 99.3%

  17. Uranium Isotopes U-234 trace U-235 0.72% U-238 99.3% Let’s try this isotope…

  18. Nuclear Fission: The splitting of larger atoms into smaller ones Page 313

  19. U + n U 238 92 239 92 1 0 + neutron uranium uranium nucleus nucleus

  20. U + n U 238 92 239 92 1 0 + neutron uranium uranium nucleus nucleus By the way, is this a chemical or nuclear process?

  21. [ 238 92 + 239 92 [ 1 0 U U n [ 0 -1 239 93 β Np + 239 92 [ U t1/2 = 2.4 days 0 -1 239 94 β Pu + 239 93 Np t1/2 = 24,100 years

  22. [ 238 92 + 239 92 [ 1 0 U U n [ 0 -1 239 93 β Np + 239 92 [ U Is this fission? t1/2 = 2.4 days 0 -1 239 94 β Pu + 239 93 Np t1/2 = 24,100 years

  23. Uranium Isotopes U-234 trace U-235 0.72% U-238 99.3% U-238 is not fissionable

  24. Uranium Isotopes U-234 trace U-235 0.72% U-238 99.3% Let’s try this isotope…

  25. Nuclear Fission: The splitting of larger atoms into smaller ones Page 313

  26. + Neutron Uranium-235 Nucleus

  27. + Neutron Uranium Nucleus Is this nuclear fission?

  28. + Neutron Uranium Nucleus YES, but this equation isn’t complete… Is this nuclear fission?

  29. LOTS of energy! + Neutron Uranium Nucleus YES, but this equation isn’t complete… Is this nuclear fission?

  30. Uranium Isotopes U-235 IS fissionable U-234 trace U-235 0.72% U-238 99.3% U-238 is not fissionable

  31. Nuclear Fission LOTS of energy! + Neutron Uranium-235 Nucleus

  32. Nuclear Fission LOTS of energy! + Neutron Uranium-235 Nucleus Let’s look closer.

  33. We begin with • A large nucleus • A neutron

  34. We begin with • A large nucleus • A neutron We end up with • Two smaller nuclei • Three neutrons • ENERGY

  35. We begin with • A large nucleus • A neutron We end up with • Two smaller nuclei • Three neutrons • ENERGY These are all EQUALLY important!

  36. Nuclear Fission LOTS of energy! Ba-138 + Neutron Uranium-235 Nucleus Kr-95

  37. Nuclear Fission LOTS of energy! Ba-138 + Neutron Uranium-235 Nucleus Kr-95

  38. [ [ 235 92 1 0 n 236 92 U + U [ [ 236 92 138 56 95 36 n 1 0 U Ba Kr 3 + +

  39. [ [ 235 92 1 0 n 236 92 U + U [ [ 236 92 138 56 95 36 n 1 0 U Ba Kr 3 + + Mass numbers: 236 = 138 + 95 + (3 * 1) Protons: 92 = 56 + 36 + (3 * 0)

  40. [ This is just one of MANY possibilities! [ 235 92 1 0 n 236 92 U + U [ [ 236 92 138 56 95 36 n 1 0 U Ba Kr 3 + + + ENERGY

  41. [ This is just one of MANY possibilities! [ 235 92 1 0 n 236 92 U + U [ [ 236 92 138 56 95 36 n 1 0 U Ba Kr 3 + + + ENERGY 90 38 143 54 n 1 0 Sr Xe 3 + ENERGY + + 131 53 102 39 n 1 0 I Y 3 + + + ENERGY

  42. [ This is just one of MANY possibilities! [ 235 92 1 0 n 236 92 U + U [ [ 236 92 138 56 95 36 n 1 0 U Ba Kr 3 + + + ENERGY 90 38 143 54 n 1 0 Sr Xe 3 + ENERGY + + 131 53 102 39 n 1 0 I Y 3 + + + ENERGY

  43. Chemistry in Context Website http://chemincontext.eppg.com/chapter7/cic_interface7.swf Lots of great animations here!

  44. Why are the neutrons important?

  45. They start a chain reaction! Why are the neutrons important?

  46. Where was the site of the first nuclear chain reaction?

  47. Where was the site of the first nuclear chain reaction? Under the bleachers at Stagg Field at the University of Chicago (December 1942)

  48. They start a chain reaction! Why are the neutrons important?

  49. Nuclear Fission LOTS of energy! Ba-138 + Neutron Uranium-235 Nucleus Kr-95 What if there are more U-235 nuclei around?

  50. LOTS of energy! Ba-138 Kr-95 U-235

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