The atom has three particles
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Due to the electrically charged electron cloud on the outside of the atom it is very difficult to smash other particles into the nucleus. Only a particle with no electrical charge can easily reach the nucleus. In 1932 Chadwick (pictured at left) discovers the neutron which has no charge. |
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In December of 1938 Otto Hahn, Lise Meitner, and Frederick Strassmann split U-235 atoms by bombarding them with neutrons. These extra neutrons cause the nucleii to become unstable which causes fission. |
This is the equation for the fission reaction that they saw
Each Uranium 235 atom needs a neutron to split. After it splits, each atom gives off three neutrons. This means that each atom that splits can split three more atoms. This can keep going causing a chain reaction.
This is a simulated picture with only two neutrons coming out.
There are two types of chain reactions. One is called controlled the other uncontrolled.
This is an example of uncontrolled chain reaction
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It is quickly realized that the products of these reactions weigh less than the reactants. This means that a fission reaction will produce a large amount of energy according to Einstein's equation E=mc2. Hear Einstein explain this equation in his own words. |
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If the products of a nuclear reaction weigh less than the reactants, this means that the mass did not simply disapear, but was converted into energy. A tiny little mass difference amounts to a large amount of energy because c2 in Einstein's equation is equal to 9000000000000000000 m2/s2. |
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