1. Nuclear Chemistry Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

2. 2 X A Z Mass Number Atomic Number Element Symbol Atomic number (Z) = number of protons in nucleus Mass number (A) = number of protons + number of neutrons = atomic number (Z) + number of neutrons A Z 1p1p 1 1H1H 1 or proton 1n1n 0 neutron 0e0e 00 or electron 0e0e +1 00 or positron 4 He 2 44 2 or  particle 1 1 1 0 0 0 +1 4 2 Review

3. 3 Balancing Nuclear Equations 1.Conserve mass number (A). The sum of protons plus neutrons in the products must equal the sum of protons plus neutrons in the reactants. 1n1n 0 U 235 92 + Cs 138 55 Rb 96 37 1n1n 0 ++ 2 235 + 1 = 138 + 96 + 2x1 2.Conserve atomic number (Z) or nuclear charge. The sum of nuclear charges in the products must equal the sum of nuclear charges in the reactants. 1n1n 0 U 235 92 + Cs 138 55 Rb 96 37 1n1n 0 ++ 2 92 + 0 = 55 + 37 + 2x0

4. 4 212 Po decays by alpha emission. Write the balanced nuclear equation for the decay of 212 Po. 4 He 2 44 2 or alpha particle - 212 Po 4 He + A X 84 2Z 212 = 4 + AA = 208 84 = 2 + ZZ = 82 212 Po 4 He + 208 Pb 84 282

5. 5

6. 6 Nuclear Stability and Radioactive Decay Beta decay 14 C 14 N + 0  6 7 40 K 40 Ca + 0  19 20 1 n 1 p + 0  0 1 Decrease # of neutrons by 1 Increase # of protons by 1 Positron decay 11 C 11 B + 0  6 5 +1 38 K 38 Ar + 0  19 18 +1 1 p 1 n + 0  1 0 +1 Increase # of neutrons by 1 Decrease # of protons by 1

7. 7 Electron capture decay Increase number of neutrons by 1 Decrease number of protons by 1 Nuclear Stability and Radioactive Decay 37 Ar + 0 e 37 Cl 18 17 55 Fe + 0 e 55 Mn 26 25 1 p + 0 e 1 n 1 0 Alpha decay Decrease number of neutrons by 2 Decrease number of protons by 2 212 Po 4 He + 208 Pb 84 282 Spontaneous fission 252 Cf 2 125 In + 2 1 n 98 490

8. 8 n/p too large beta decay X n/p too small positron decay or electron capture Y

9. 9 Nuclear Stability even numbersNuclei with even numbers of both protons and neutrons are more stable than those with odd numbers of neutron and protons All isotopes of the elements with atomic numbers higher than 83 are radioactive

10. 10 Radioactive Decay A = A o x (1/2) n A = amount remaining A o = initial amount n = number of half lives

11. 11 Lead-210 has a half life of 20.4 years. If an initial sample contains 5 g of this isotope, how much is left after 47.2 years? A = 1.0 grams

12. 12

13. 13 Radiocarbon Dating 14 N + 1 n 14 C + 1 H 716 0 14 C 14 N + 0  + 6 7 t ½ = 5730 years Uranium-238 Dating 238 U 206 Pb + 8 4  + 6 0  92822 t ½ = 4.51 x 10 9 years

14. 14 Nuclear Transmutation 14 N + 4  17 O + 1 p 7 2 8 1 27 Al + 4  30 P + 1 n 13 2 15 0 14 N + 1 p 11 C + 4  7 1 6 2

15. 15 Nuclear Transmutation

16. 16 Nuclear Fission 235 U + 1 n 90 Sr + 143 Xe + 3 1 n + Energy 92 54 3800

17. 17 Nuclear Fission 235 U + 1 n 90 Sr + 143 Xe + 3 1 n + Energy 92 54 3800 Representative fission reaction

18. 18 Nuclear Fission Nuclear chain reaction is a self-sustaining sequence of nuclear fission reactions. The minimum mass of fissionable material required to generate a self-sustaining nuclear chain reaction is the critical mass.

19. 19 Schematic of an Atomic Bomb

20. 20 Schematic Diagram of a Nuclear Reactor U3O8U3O8 refueling

21. 21 Nuclear Fusion 2 H + 2 H 3 H + 1 H 1 1 1 1 Fusion ReactionEnergy Released 2 H + 3 H 4 He + 1 n 1 1 2 0 6 Li + 2 H 2 4 He 3 1 2 6.3 x 10 -13 J 2.8 x 10 -12 J 3.6 x 10 -12 J Tokamak magnetic plasma confinement solar fusion

22. 22 Thyroid images with 125 I-labeled compound normalenlarged

23. 23 Radioisotopes in Medicine 98 Mo + 1 n 99 Mo 42 0 235 U + 1 n 99 Mo + other fission products 92042 99m Tc 99 Tc +  -ray 43 99 Mo 99m Tc + 0  42 43 Research production of 99 Mo Commercial production of 99 Mo t ½ = 66 hours t ½ = 6 hours Bone Scan with 99m Tc

24. 24 Biological Effects of Radiation Radiation absorbed dose (rad) 1 rad = 1 x 10 -5 J/g of material Roentgen equivalent for man (rem) 1 rem = 1 rad x QQuality Factor  -ray = 1  = 1  = 20

25. 25 Chemistry In Action: Food Irradiation