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Nuclear Reactions. We need to balance equations just like we do for chemical reactionsWe can nucleons, which are conservedWe count charges, which are conservedWe have to conserve energy and momentum and angular momentum. Rutherford observed the first nuclear reaction with alpha particlesWe often write this in shorthand as.
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1. Nuclear Reactions We can transform one element into another via a nuclear reaction
We just talked about changing nitrogen into C-14 via n + N-14 -> C-14 + p
This is called a transmutation
Enormous number of possible reactions
3. Rutherford observed the first nuclear reaction with alpha particles
We often write this in shorthand as Nuclear Reactions
4. Nuclear Reactions Reactions can be exothermic or endothermic
Use E=mc2
Sum the energies of the reactants and the energies of the products
The difference will be positive or negative
5. Nuclear Reactions
6. Neutrons & Uranium Bombard U-238 nuclei with neutrons
Two different sets of processes occur
The first is simple neutron capture and subsequent decay of the resulting U-239 into a new element, neptunium-239
The neptunium subsequently decays into another new element, plutonium-239
7. Neutrons and Uranium
8. Neutrons & Uranium The second process that occurs is much more remarkable!!
The uranium essentially broke approximately in half and yielded a variety of nuclei of barium, krypton, xenon, tin, molybdenum, strontium and additional neutrons!!!
A model for the nucleus, the liquid drop model was developed to explain the results
9. Neutrons & Uranium
10. Neutrons & Uranium
11. Neutrons & Uranium
12. Nuclear Fission U-235 fissions and U-238 captures neutrons and produces plutonium which also fissions
Make a nuclear reactor to produce a controlled fission process
Absorb two of the neutrons that come out so only one goes on to produce another fission
Use cadmium as the absorber
13. Nuclear Fission If you dont mop up the neutrons, the reaction can run away
Then you have an fission bomb
Can do with either U-235 or Pu-239
Simply have to create a critical mass so that the neutrons can multiply
14. Nuclear Fission
15. Nuclear Fusion Go to the other end of the scale
Put small nuclei together to form bigger ones and also get energy output
Lets look once again at the binding energy graph
16. Nuclear Fusion
17. Nuclear Fusion Powers the sun and stars with various cycles leading to iron