Fission vs Fusion Fission heavy nuclei are split

Fission vs. Fusion • Fission – heavy nuclei are split into lighter nuclei – Fission reactions are relatively easy to control but produce radioactive wastes. • Fusion – Light-weight nuclei are combined to form heavier nuclei. – Fusion reactions are difficult to initiate and control but produce little radioactive wastes.

Fission U-235

Dangers of Nuclear Power • Chernobyl, Russia – 400 times more nuclear fallout than the nuclear bombing of Hiroshima – Unclear how many people have developed Cancer • Three Mile Island, New Jersey

Fusion Deuterium Tritium

Uses for Nuclear Rxns • • Electricity Carbon-14 Dating Radiation Therapy Medical Imaging

Half-Life • The length of time it takes for one-half of the atoms of a radioactive nuclide to disintegrate.

Half-Life Table Nuclide Half-Life Decay Type 0. 802 seconds Beta 1. 3 minutes Alpha and Gamma 12. 3 yrs. Beta 5730 yrs. Beta 7. 1 x 108 yrs. Alpha and Gamma

Example • The half-life of Zn-71 is 2. 4 minutes. If one had 100. 0 g at the beginning, how many grams would be left after 7. 2 minutes has elapsed? Time (min) Mass (g) 0 100. 0 2. 4 50. 0 4. 8 25. 0 7. 2 12. 5

Example 2 • After 24. 0 days, 2. 00 milligrams of an original 128. 0 milligram sample remain. What is the half-life of the sample? ½ Lives Mass (mg) 0 128. 0 1 64. 0 2 32. 0 3 16. 0 4 5 8. 0 4. 0 6 2. 0 6 x=24 days x=4 days ½ life= 4 days

Example 3 • What is the half-life of the substance based on the following graph? ½ life = 2. 5 yrs