Explain in brief, nuclear fission.

i. Nuclear fission : 

It is a process which involves splitting of the heavy nucleus of an atom into two nearly equal fragments accompanied by release of the large amount of energy. 

e.g. Nuclear fission of ²³⁵U

ii. When a uranium nucleus absorbs neutron,

It breaks into two lighter fragments and releases energy (heat), more neutrons, and other radiation. 

This can be given as,

\(_{92}^{235}U\) + \(_0^1n\) → \(_{56}^{142}Ba\) + \(_{36}^{91}Kr\) + \(3_0^1n\) + Energy

iii. Characteristics of nuclear fission reactions :

• The mass of the fission products is less than the parent nucleus. A large amount of energy corresponding to the mass loss is released in each fission.
• When one uranium 235 nucleus undergoes fission, three neutrons are emitted, which subsequently disintegrate three more uranium nuclei and thereby produce nine neutrons. Such a chain continues by itself.
• In a very short time enormous amount of energy is liberated, which can be utilized for destructive or peaceful purposes.
• Energy released per fission is approximately 200 MeV.

 Note :

• Each fission may lead to different products.
• There is no unique way for fission of ²³⁵U that produces Ba and Kr. There are 400 ways for fission of ²³⁵U leading to 800 fission products.
• Many of these fission products are radioactive which undergo spontaneous disintegrations giving rise to new elements in the periodic table.