Fisson is a nuclear process where a neutron collides in to a heavy nucleus
and splits it into two smaller nuclei
An example of a fission reaction that was used in the first atomic bomb
and is still used in nuclear reactors is
235U + n ----> 134Xe + 100Sr + 2n
A large amount of energy us released once the nucleus is split because
of the binding energy holding the nucleus together. With most elements
Fission is impossible because the nuclei are too tightly bound. However,
some elements like Uranium are made of larger unstable nuclei that easily
break apart. By harnessing this released energy it can be used as a source
of nuclear power.
Fission occurs because of the electrostatic
repulsion created by the large number of positively charged protons contained
in a heavy nucleus. Two smaller nuclei have less internal electrostatic
repulsion than one larger nucleus. So, once the larger nucleus can overcome
the strong nuclear force which holds it together, it can fission. Fission
can be seen as a "tug-of-war" between the strong attractive nuclear force
and the repulsive electrostatic force. In fission reactions, electrostatic
repulsion wins.
Fission is a process that has been occurring
in the universe for billions of years. As mentioned above, we have not
only used fission to produce energy for nuclear bombs, but we also use
fission peacefully everyday to produce energy in nuclear power plants.
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