1. Chapter 23 N UCLEAR C HEMISTRY Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

2. C HEMICAL VS N UCLEAR R EACTIONS

3. 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 N UCLEAR S YMBOLS

4. D ECAY P ARTICLES  Alpha(α) Particle  2 protons and 2 neutrons Helium nucleus  Gamma() Particle  Energy that accompanies a decay reaction 4 He 2 44 2 or 0γ0γ 0

5. D ECAY P ARTICLES  Beta( β ) Particles  electron  Positron 0e0e 00 or 0e0e +1 00 or

6. O THER P ARTICLES  Proton  Neutron 1p1p 1 1H1H 1 or 1n1n 0

7. 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 B ALANCING N UCLEAR E QUATIONS

8. 212 Po decays by alpha emission. 212 Po + 84 212 Po 4 He + 208 Pb 84 282 P RACTICE P ROBLEM In radioactive decay steps, the beginning radioactive isotope is called the parent and the product is called the daughter.

9. U RANIUM D ECAY S ERIES

10. Beta decay 14 C 14 N + 0  + 6 7 Positron decay 11 C 11 B + 0  + 6 5 +1 D ECAY E XAMPLES Electron capture decay 37 Ar + 0 e 37 Cl + 18 17 Alpha decay 212 Po 4 He + 208 Pb 84 282

11. Cyclotron Particle Accelerator 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 N UCLEAR T RANSMUTATION Bombarding an element with particles to produce new elements

12. n/p too large beta decay X n/p too small positron decay or electron capture Y Band of Stability

13. Certain numbers of neutrons and protons are extra stable n or p = 2, 8, 20, 50, 82 and 126 Like extra stable numbers of electrons in noble gases (e - = 2, 10, 18, 36, 54 and 86) Nuclei 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 All isotopes of Tc and Pm are radioactive N UCLEAR S TABILITY

14. N UCLEAR B INDING E NERGY Nuclear binding energy (BE): energy required to break up a nucleus into its component protons and neutrons. Einstein’s energy mass relationship: E = mc 2 Links energy and mass calculations

15. BE + 19 F 9 1 p + 10 1 n 9 1 0 BE = 9 x (p mass) + 10 x (n mass) – 19 F mass BE (amu) = 9 x 1.007825 + 10 x 1.008665 – 18.9984 BE = 0.1587 amux 1.49 x 10 -10 J 1 amu = 2.37 x 10 -11 J binding energy per nucleon = binding energy number of nucleons = 2.37 x 10 -11 J 19 nucleons = 1.25 x 10 -12 J H OW TO C ALCULATE BE

16. nuclear binding energy nucleon nuclear stability N UCLEAR BINDING ENERGY PER NUCLEON VS M ASS NUMBER

17. N UCLEAR F USION  Combining of small nuclei to form larger ones  Occurs in stars at high temperatures  Called a thermonuclear reaction

18. N UCLEAR F ISISON  Breaking down of a large massive atom into smaller ones  Nuclear chain reaction: self-sustaining sequence of nuclear fission reactions.  critical mass: minimum mass of fissionable material required to generate a self-sustaining nuclear chain reaction

19. Non-criticalCritical T WO T YPES OF F ISSION

20. Schematic diagram of a nuclear fission reactor C ONTROLLED N UCLEAR F ISSION

21. G EIGER -M ÜLLER C OUNTER