Chapter 21 Nuclear Chemistry

1. Chapter 21Nuclear Chemistry 12th edition

2. 21.1 Radioactivity • Review from Ch. 2 • Subatomic particles • Atoms are neutral: # protons = # electrons • Isotopes – atoms with same number of protons but different number of neutrons

3. Nuclear Chemistry deals with only the nucleus. • radioactivity – spontaneous emission of radiation • nuclide– nucleus with specified number of protons and neutrons • radionuclide – radioactive nuclide • radioisotopes– atoms containing radioactive nuclei • radioactive decay – spontaneous decomposition to form a different, more stable, nucleus with the production of one or more particles • decay series – multiple decay steps through which radioactive nuclides go to reach a stable state

4. Decay Series

5. Common Particles in Radioactive Decay and Nuclear Reactions

6. Fission of 235U initiated by neutron capture

7. Chain Fission Reaction

8. Nuclear Equations – sums of both mass and atomic numbers on both sides of equation are equal Examples: 6831Ga + 0-1e → _____ 21287Fr → 20885At + ______ 263106Sg → ______ + 42He

9. 21.4 Rates of Radioactive Decay • Radioactive decay follows 1st order kinetics. • All half-lives are equal. N – # of radioactive nuclei k – decay constant Individual half-lives vary tremendously: 214Po 2 x 10-4 s 144Nd 5 x 1015 year

10. Half-lives

11. Practice exercise, p. 890

12. Practice problem 21.33

13. Practice problem, 90Sr from 1st atomic explosion

14. Mastering problem 21.41