Answer:
Nuclear fission begins when a neutron hits the nucleus of an atom. The nucleus that captures the incident neutron becomes unstable and, as a consequence, its division into lighter fragments results in a situation of greater stability. Thus thermal energy and more neutrons are released. Neutrons hit the nuclei of more atoms, dividing them and releasing more energy and neutrons. That is to say, in the fission reaction several neutrons are produced which, upon impacting on other fissile nuclei, trigger more fission reactions that in turn generate more neutrons. This multiplier effect is known as chain reaction.
Explanation:
Nuclear fission is the physical-chemical reaction through which the nucleus of an atom is split. Atomic energy is the energy contained in the nucleus of an atom and the energy obtained is thermal energy, energy in the form of heat. Then nuclear fission is a reaction in which a heavy nucleus, when bombarded with neutrons, becomes unstable and decomposes into two nuclei, whose sizes are of the same order of magnitude, with great energy shedding and the emission of two or three neutrons. Then the session of heavy elements is an exothermic reaction.
Then, <u><em>nuclear fission begins when a neutron hits the nucleus of an atom. The nucleus that captures the incident neutron becomes unstable and, as a consequence, its division into lighter fragments results in a situation of greater stability. Thus thermal energy and more neutrons are released. Neutrons hit the nuclei of more atoms, dividing them and releasing more energy and neutrons. That is to say, in the fission reaction several neutrons are produced which, upon impacting on other fissile nuclei, trigger more fission reactions that in turn generate more neutrons. This multiplier effect is known as chain reaction.
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For a chain fission reaction to occur, it is necessary that certain conditions of geometry of the fissile material be met and a certain threshold of quantity thereof, known as critical mass, be exceeded. Then the critical mass is the minimum amount of fissile material so that a nuclear chain reaction is maintained. The amount of critical mass of a fissile material depends on several factors: physical properties, nuclear properties, its geometry and its purity.
Fission can occur spontaneously, but the existence of a neutron that affects adequate energy is necessary.
