1. 24-3: Harnessing the Nucleus

2. Per gram, average energy produced by… Chemical reaction Nuclear reaction 50 kJ 1,000,000 kJ

3. Nuclear Fission Enrico Fermi: bombarded uranium with neutrons Enrico Fermi: bombarded uranium with neutrons Hahn and Strassman: repeated Fermi’s experiment, but produced barium Hahn and Strassman: repeated Fermi’s experiment, but produced barium Lise Meitner: found reason for barium impurity – first to identify a nuclear fission rxn Lise Meitner: found reason for barium impurity – first to identify a nuclear fission rxn Nuclear fission rxn: a large nucleus is split into two smaller nuclei Nuclear fission rxn: a large nucleus is split into two smaller nuclei

4. Enrico Fermi Lise Meitner

5. “Missing Mass” In a fission rxn, the mass of the products is slightly less than the mass of the reactants. In a fission rxn, the mass of the products is slightly less than the mass of the reactants. Missing mass is converted into energy: Missing mass is converted into energy: E = mc 2 E = mc 2 c = speed of light, 3 x 10 8 m/s c = speed of light, 3 x 10 8 m/s Nuclear chain rxn: series of fission rxns started by extra neutrons in one reaction Nuclear chain rxn: series of fission rxns started by extra neutrons in one reaction

7. Nuclear Reactors Nuclear power plants contain too little fuel to explode like a nuclear bomb Nuclear power plants contain too little fuel to explode like a nuclear bomb Three Mile Island (1979): scare of meltdown, due to operator error Three Mile Island (1979): scare of meltdown, due to operator error Chernobyl incident (1986): reactor destroyed, due to graphite fire (operator error); radiation leaded out, causing deaths and cancers Chernobyl incident (1986): reactor destroyed, due to graphite fire (operator error); radiation leaded out, causing deaths and cancers Nuclear waste disposal is a problem Nuclear waste disposal is a problem

8. Three Mile Island Power Plant

9. Chernobyl Power Plant

10. A Chernobyl firefighter

11. Nuclear Fusion Nuclear fusion: two small nuclei join to form a larger nucleus Nuclear fusion: two small nuclei join to form a larger nucleus Ex: Ex: Problems: repulsion of atomic nuclei to come together Problems: repulsion of atomic nuclei to come together Stripping off electrons creates plasma Stripping off electrons creates plasma Must reach high temp. in order for atoms to move together Must reach high temp. in order for atoms to move together Thermonuclear rxn: fusion with extreme heat (stars) Thermonuclear rxn: fusion with extreme heat (stars)

13. Fusion Research Temp. cannot be withstood Temp. cannot be withstood Tokamak: magnetic device needed to control temp. Tokamak: magnetic device needed to control temp.

15. Cold Fusion Cold fusion: fusion without the need for extreme heat Cold fusion: fusion without the need for extreme heat Pons and Fleishman: may have produced a cold fusion rxn with heavy water Pons and Fleishman: may have produced a cold fusion rxn with heavy water