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Chapter 3: Nuclear Chemistry

Chapter 3: Nuclear Chemistry. Radioactivity Nuclear Equations Radiation Detection Half-Life Medical Applications Fission & Fusion. -. -. -. +. +. +. Isotopes of Hydrogen. Isotopes = Atoms of the same element but having different masses. 1 1. 2 1. 3 1. H. H. H. Protium

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Chapter 3: Nuclear Chemistry

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  1. Chapter 3: Nuclear Chemistry • Radioactivity • Nuclear Equations • Radiation Detection • Half-Life • Medical Applications • 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 +

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

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

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

  13. 4 2 4 2 He He Nuclear Equations a: Radon gas in Buildings 226 88 222 Rn + Ra 86 218 Po + 84 Cancer

  14. 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

  15. 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

  16. Radiation Detection Absorbed Dose

  17. - a 0.05 mm + + 4-5 mm b >50 cm g Radiation Detection Absorbed Dose Tissue Penetration Depth

  18. - + + Radiation Absorbed Dose (Rad) (D): a 0.05 mm 4-5 mm b >50 cm 1 rad = 1 x 10-2J 1 kg tissue 1 rad = 2.4 x 10-3 cal 1 kg tissue g 100 rad = 1 Gray (Gy)

  19. Radiation Detection Biological Damage

  20. Radiation Equivalent for Man (rem) (relative biological effectiveness) a RBE 20 1 1 b g Damage (rem) = absorbed dose (rad) X factor 1 rem = 1 rad x RBE 100 rem = 1 sievert (Sv)

  21. Annual Radiation Exposure in USA Cosmic = 40 mrem Air, H2O, Food = 30 mrem X-rays: Chest = 50 mrem Dental = 20 Smoking = 35 mrem TV = 2 mrem Radon = 200 mrem Wood,concrete,bricks = 50 mrem Ground = 15 mrem

  22. Biological Effects of Radiation Dose in rem 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

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

  24. 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 # of half lifes Mass remaining m = g(0.5)t Beginning mass

  25. Half-Life 131 53 I How much I-131 will be left after 72 days? t1/2 = 8 days 8 days 5.0 g 10. g 20. g 72 days 1 1 half-life = 8 days 9 half-lifes m = g(0.5)t = 20. g(0.5)9 = .039 g

  26. Positron Emission Tomography • PET

  27. 91 36 Kr 235 92 236 92 1 0 U U n 142 56 Ba Fission Splitting atoms for Energy Energy + unstable

  28. Fission Need critical mass of U-235

  29. 2 1 4 2 3 1 1 0 + He H n H + + + Fusion Combining atoms for Energy Energy Deuterium + + Tritium

  30. Fusion

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