Nuclear Reactions

Nuclear Reactions

by Rohan Mathew

Nuclear reactions are collisions between subatomic particles, one atomic nucleus, or two atomic nuclei, which produce one or more nuclides. Nuclear reactions contain nuclides that are different from the nuclei that are reacting.

There are several nuclear reactions, in which two important nuclear reactions are nuclear fusion reaction and nuclear fission reaction. Nuclear fusion is when two or lighter nuclei collide and fuse to create a heavier nucleus. This reaction occurs when low-atomic-number elements, like hydrogen, are combined. Nuclear fission occurs as the nucleus of an atom breaks into smaller nuclei due to a nuclear reaction.

Types of Nuclear Reactions

There are several nuclear reactions, and the four most common ones are described below.

  • Nuclear Fission

The division of an atomic nucleus into two or lighter nuclei is referred to as nuclear fission. It can happen as a result of a nuclear reaction or as a result of radioactive decay. Nuclear fission processes also release a significant amount of energy, and also gamma radiation and neutrons.


The splitting of Uranium-233 is an example of nuclear fission. The reaction equation expressed below.

235U + 1n → 144Xe + 90Sr + 2 1n

235U + 1n → 137Cs + 96Rb + 3 1n

  • Nuclear Fusion

In nuclear fusion reactions, at least two atomic nuclei fuse to form a single nucleus. As a result of these nuclear reactions, subatomic particles such as neutrons and protons are formed. Such reactions can be found in the centres of stars like the sun and other stars.


The sun’s centre has a temperature of about 15 million degrees Celsius. Two isotopes of hydrogen, Deuterium and Tritium, combine at high pressure to form Helium, which releases a large amount of energy in the form of heat.

  • Nuclear Decay

Nuclear decay is also known as radioactive decay. As the nucleus of an atom becomes unstable, it naturally releases energy in radiation, which is known as nuclear decay. Consequently, the nucleus of one or more other elements becomes the nucleus of one or more other elements. Such daughter nuclei are much more stable and have a lower mass than the parent nucleus. 

  • Transmutation

Transmutation changes the number of protons in an atom’s nucleus to create a bit with a different atomic number. Since it is also transforming one element into another, the phase of transmutation can be described as a chemical reaction. 

Transmutation causes the release of a variety of particles with varying degrees of energy. Since these particles will continue the process, transmutations are often referred to as chain reactions. In certain transmutation equations, an element captures its electron and transforms into a new element. It is known as K-capture, and it is the same process that transforms Ruthenium to Tc.

100Ru44  + 0e-1100 Tc43

Transmutation causes unstable radioactive nuclei to transform into stable nuclei, preventing stable isotopes from decaying spontaneously. The nucleus is more stable when the binding energy per nucleon is high, and nuclei with a 1:1 neutron to proton ratio are also very stable. Natural transmutation does not usually require such nuclei.


A nuclear reaction is a reaction that leads to changes in the identification of an atomic nucleus caused by bombarding it with an energetic particle. Gamma-ray photons, alpha particles, protons,  neutrons or a heavy-ion could be used to bombard the particle.

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