1. Fission and Fusion Nuclear Chain Reactions

2. Nuclear Fission Fission means to split apart… the nucleus breaks into smaller fragments Uranium-235 and Plutonium-239 are the only fissionable isotopes.

3. Nuclear Fission Describe the changes taking place in the diagram

4. Nuclear Fission – Chain Reaction Some of the neutrons released react with other fissionable atoms, producing more neutrons which react with more fissionable atoms… etc.

5. Fission is used in nuclear power plants The energy released from fission is used to produce steam which spins a turbine, which turns a generator.

6. Nuclear energy produces very little waste… Vast amounts of energy are released from small amounts of fuel. No “greenhouse gases” are produced. Nuclear waste remains radioactive for hundreds of thousands of years. Must be stored securely… Damaged powerplants can release radiation into surrounding environment. (rare but…)

7. Nuclear Fusion Fusion means to join together. Nuclei combine to form produce a nucleus with a greater mass. Fusion can release much more energy than fission. Powers the sun and stars… Requires extremely high temp. to start reaction…

8. Nuclear Fusion Equations Describe what is happening in each and fill in the missing parts

9. Half-Life The time it takes for half of the radioactive atoms in a sample to decay into atoms of a new element. Shown to be an extremely consistent measure of time. Can be used to calculate the age of rocks, fossils etc. Has established the age of the Earth…4.6 billion years old.

11. If I have 1000 atoms, how many will remain after two half lives? Will I ever have zero atoms left? Explain.

12. Half life can be very long Uranium-238, T 1/2 = 4.5 x 10 9 years.

13. Calculations…YES!!! Carbon-14 has a half-life (T1/2) of 5730 years. If you start with a mass of 2.00 x 10 -12 g… How long is 3 half-lives? How many grams remain at the end of 3 half- lives?