What keeps the nucleus from flying apart? The Coulomb force acts so that two positive charges repel each other so protons normally would push each other away. But the Strong force acts within the nucleus to hold nucleons together. The Strong force acts on both protons and neutrons. The range of the Strong Force is near the diameter of the nucleus. This limited range of the strong force keeps the nucleus from becoming too large. The larger the number of nucleons the more unstable the nucleus becomes. If a slow neutron is captured by atoms with large atomic masses then the atom breaks apart releasing large amounts of energy.
One of the most controversial of all sources of energy is the nuclear fission process. In 1939, Otto Hahn, Fritz Strassman and Liza Mitner discovered that unceratin conditions a uranium nucleus can split into two smaller nuclei. This process called nuclear fission releases a great deal of energy, more than had been released in any process before this time. The first step occurs when a slow neutron is absorbed by a uranium 235 nucleus.
In absorbing the slow neutron, the nucleus is in an excited state. It vibrates and oscillates becoming very distorted. It breaks into smaller "pieces" under the stress of the motion. Two "daughter" nuclei are formed and two or more neutrons are released to continue the process.
Binding energy is also released in this transmutation.
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