Nuclear fission occurs when an atom splits into two or more smaller atoms, most often the as the result of neutron bombardment. Nuclear ﬁssion is a process by which the nucleus of an atom is split into two or more smaller nuclei, known as ﬁssion products. The ﬁssion of heavy elements is an exothermic reaction, and huge amounts of energy are released in the process.
The nuclei produced are most often of comparable but slightly different sizes, typically with a mass ratio of products of about 3:2 for common fissile isotopes. Most fissions are binary fissions that produce two charged fragments. Occasionally, about 2 to 4 times per 1000 events, three positively charged fragments are produced, which indicates a ternary fission. The smallest of these fragments in ternary processes ranges from the size of a proton to the size of an argon nucleus.
Nuclear fission: In nuclear fission, an unstable atom splits into two or more smaller pieces that are more stable, and releases energy in the process. The fission process also releases extra neutrons, which can then split additional atoms, resulting in a chain reaction that releases a lot of energy. There are also ways to modulate the chain reaction by soaking up the neutrons.