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Chapter 13 : Nuclear Chemistry

Chapter 13 : Nuclear Chemistry

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Chapter 13 : Nuclear Chemistry

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  1. Chapter 13: Nuclear Chemistry • Radioactivity • Nuclear Equations • Radiation Detection • Half-Life • Medical Applications • Radiometric Dating • Fission & Fusion

  2. - - - + + + Isotopes of Hydrogen • Isotopes = Atoms of the same element but having different masses. 1 1 2 1 3 1 H H H Protium 99.99% Tritium Trace % Deuterium 0.01% Average Atomic weight of Hydrogen = 1.00794amu

  3. 12 13 14 C C C 6 6 6 - - - - - - + + + - + + + + + + + + + - - + + + + + + - - - - - - - Isotopes of Carbon - - 98.89% 1.11% Trace % Average Atomic weight of C= 12.011amu

  4. 14 3 1 C H 6 - - + + + + + - + + - - Radioactive Isotopes - - Hydrogen-3 Carbon-14 Nucleus is unstable So falls apart (decays) Giving radioactive particles

  5. 123 53 131 53 I I 60 27 Co 99m Tc 43 Radioactive Isotopes in Medicine Diagnose thyroid function Treat hyperthyroid (destroys cells) Destroy tumors (g radiation) Diagnose bone, tissue (most common)

  6. 210 84 210 84 206 206 Pb Pb Po Po 82 82 + + + + + + + + 4 2 4 2 He He Alpha Decay a Particle Transmutation: one element changes to another +

  7. 14 6 14 - N C 7 + + + + + + + + 1 1 1 0 0 -1 0 -1 + e n H e + + + + Beta Decay b Particle + - + neutron proton electron

  8. 14 6 14 6 14 14 - N N C C 7 7 + + + + + + + + 0 -1 0 -1 + e e + + + + Beta Decay b Particle + - +

  9. 99m 43 99m 43 99 43 99 Tc Tc Tc Tc 43 + + + + + + + + + + + + Gamma Decay g decay g +

  10. - Ionizing Radiation Radiation knocks off an electron An ion A radical Ions & radicals cause damaging chain reactions

  11. - Geiger Counter Radiation knocks off an electron An ion Gas in instrument tube Ions detected by Counter

  12. - + + Radiation: Penetration through Air a 2 - 4 cm b 200 - 300 cm 500 m g

  13. - + + Radiation: Shielding Heavy Cloth a Pb, thick concrete Paper Cloth b g

  14. - + + Tissue Penetration Depth a 0.05 mm 4-5 mm b >50 cm g

  15. 4 2 4 2 He He Nuclear Equations a: Radium Radon gas in Buildings 226 88 222 Rn + Ra 86 218 Po + 84 Cancer

  16. 60 27 Co 0 -1 0 -1 e e 131 53 I Nuclear Equations b: Cancer Treatment 60 Ni + 28 b: Thyroid check & treatment 131 Xe + 54

  17. Radiation Detection Activity # of disintegrations by of 1g Ra Curie (Ci): 1 Ci = 3.7 x 1010disintegrations sec Becquerel (Bq) 1 Bq = 1 disintegration sec

  18. Radiation Detection Absorbed Dose

  19. Tissue Penetration Depth - a 0.05 mm 0.06-5 mm b + + >50 cm g Radiation Detection: Biological Effect Radiation Absorbed Dose (Rad) (D): 1 rad = 0.0024 cal kg tissue 1 rad = 0.01 J kg tissue 100 rad = 1 Gray

  20. Radiation Detection Biological Damage

  21. Roentgen Equivalent for Man (rem) Quality Factor Radiation Weighting factor a WR 20 1 1 b g Damage (rem) = absorbed dose (rad) X factor 1 rem = 1 rad x RBE 100 rem = 1 sievert (Sv)

  22. Annual Radiation Exposure in USA Total = 170 - 360 mrem / yr Cosmic = 26-40 mrem Air, H2O, Food = 30 mrem X-rays: Chest = 50 mrem Dental = 20 Smoking = 35 mrem TV/computers = 12 mrem Radon = 200 mrem Wood,concrete,bricks = 50 mrem Ground = 15-30 mrem

  23. Annual Radiation Exposure in USA

  24. Biological Effects of Radiation Dose in rem (at one time) 0-25genetic damage possible but usually undetected 25-100 decrease # of white blood cells (temporary) 100-200 mild radiation sickness (vomit, diarrhea, strong decrease # white blood cells) >300 (diarrhea, hair loss, infection) 500 LD50 for humans

  25. Biological Effects of Radiation Dose in rem 300 LD50 for dogs 800 LD50 for rats 50,000 LD50 for Bacterium 100,000 LD50 for Insects 500 LD50 for humans

  26. Therapeutic Doses of Radiation Dose in rem 4,500 Lymphoma 5,000 – 6,000 Skin cancer 6,000 Lung cancer 6,000 – 7000 Brain Tumor

  27. FDA approved killing of bacteria with: 0.3 – 1 kGy ionizing radiation from Co-60 or Cs-137 (gamma producers)

  28. 131 53 I Half-Life t1/2 = Time for 1/2 sample to decay t1/2 = 8 days 8 days 5 g 10 g 20 g

  29. Half-Life I-131 8 days Co-60 5.3 yrs Tc-99m 6 hrs Ra-226 1620 yrs

  30. 131 53 I Half-Life t1/2 = Time for 1/2 sample to decay t1/2 = 8 days 8 days 5 g 10 g 20 g

  31. 0 -1 e 55 24 55 24 Cr Cr Half-Life Chromium-55 undergoes beta decay wth a half life of 3.5 minutes. What is the primary identity of the sample after decay? 55 Mn + 25 If you start with 120 g; How much Cr-55 will be left after 14 minutes? t1/2 = 3.5 min 3.5 min 3.5 min 3.5 min (7 min Total) (10.5 min Tot) (14 min Total) 15 g 7.5 g 60 g 30 g 120 g

  32. Natural Decay Series of Uranium-238

  33. 0 -1 4 2 e He 238 92 234 90 Th U Natural Decay Series of Uranium-238 234 Th + 90 234 Pa + 91

  34. Natural Decay Series of Uranium-238

  35. Radiometric Dating

  36. Artificial Transmutation

  37. Positron Emission Tomography (PET) 0 +1 e 11 6 + C + + + 0 + + + + + 11 + B 0 1 1 1 0 5 H n + + 0 +1 e b+ Positron + proton neutron positron

  38. Positron Emission Tomography (PET) 0 -1 0 +1 e e 11 6 - + C + + + 0 + + + + + 11 + B 0 5 + + 11 5 0 +1 e B electron 2g rays b+ Positron Detectable g rays  image Shows blood flow 11 6 C + positron

  39. Positron Emission Tomography (PET) 0 -1 0 +1 e e 11 6 - + C + + + 0 + + + + + 11 + B 0 5 + + 0 +1 0 -1 e e 2g electron 2g rays b+ Positron Detectable g rays  image Shows blood flow + positron electron gamma

  40. 91 36 Kr 235 92 236 92 1 0 U U n 142 56 Ba Fission Splitting atoms for Energy Energy + unstable • Uses: • Atomic Bomb • Nuclear Power

  41. 235 92 U

  42. 235 92 U

  43. 235 92 U

  44. 235 92 U

  45. 236 92 U