10.2 Nuclear Forces
• forces between protons and ______in the nuclei of atoms • the stability of the nucleus depends on these forces
Strong Nuclear Force holds protons (+) and neutrons (no charge) together
In a stable atom, the attractive forces are stronger than the repulsive forces, and the element does not undergo decay.
Too many neutrons or protons can cause a nucleus to become ______and ______.
Example: nuclei with > 83 protons are always unstable and decay REMEMBER, decay results in more stable nuclei.
Definition: process of splitting heavier nuclei into lighter nuclei
• During fission, both neutrons and energy are released.
Albert Einstein explained how matter can be converted into energy and energy into matter with his theory of relativity in 1905.
E = mc2
2 Chain Reactions (Fission)
Analogy: shooting marbles or dominoes
Neutron strikes a nuclei > splits > neutrons are emitted and strike other nuclei causing them to split
If every Uranium atom emits 2 neutrons when split, then these neutrons can split 2 more U atoms, which will produce more neutrons to split add'l atoms, etc.
3 This sounds like how Nuclear Reactors work: a controlled chain reaction can be used to generate electricity by using the energy given off to heat water, which makes steam, which rotates a turbine to generate electricity.
Control rods are used to regulate fission by slowing down the chain reaction.
4 The Power of Fission
• U.S. receives about 20% of its power from nuclear power plants.
• Around the world, there are 440 nuclear reactors that generate electriticy, > 400 that power ships and submarines, and a bit less than 300 that are used for research.
• France is the world's leader in using nuclear power for electricity (>75%).
5 Nuclear Fusion Definition: combining light nuclei to form heavier nuclei.
• This process occurs in the sun (Hydrogen nuclei fuse to make Helium) and is used to make nuclear bombs. • A LOT of energy is needed to start a fusion reaction. • Major problem with fusion: must occur at VERY high temperatures (100's of millions of C).
http://www.cosmolearning.com/videos/fissionandfusion/
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