Difference Between Homolytic And Heterolytic Fission

What is fission?

There is a release in energy when an atom splits into two parts. This process is known as fission. It has enormous potential as a source of power but sometimes it is dangerous for the environment so it should be cautiously done. In fission, the nucleus splits by any radioactive decay or bombardment with other atoms which results in the release of particles which has mass lesser than the original mass of nucleus as nuclear energy is converted from the missing mass. We are going to learn about two types of fission in this post which are homolytic and heterolytic.

Heterolytic Fission

Heterolytic fission:

In heterolytic fission, when a covalent bond is broken, the shared pair of electron is taken by one of the atoms. This is the fission in which the electrons are not divided equally. The negatively charged atom has octet configuration in this type of fission whereas the positively charged atom has sextet configuration. In this type of cleavage, we also get carbon atoms which are negatively charged and are also called as carbanions and in the same way the carbon atoms which are positively charged, known as carbocations. The carbocations are trigonal in shape and are sp2 hybridized. Carbocations are formed due to heterolysis of C-X bond and these are very reactive towards electron rich species. Carbanions are sp3 hybridized and are reactive towards a positive charge.

An example of heterolytic fission is when a hydrochloric acid is cleaved then both the bonded electrons are taken by chlorine and a negative ion which can be shown as Cl.

                        H-Cl   →      H+ + Cl

 Homolytic fission:

Homolytic fission is that fission in which each atom in the bond has an electron which results in species called free radicals.  Homolytic fission is symmetrical in nature and leads to the formation of atoms or groups of atoms that has unpaired electrons. During the homolytic fission of a neutral molecule, two free radicals is generated if the number of electrons is even in the molecule.

These types of reactions can be induced by UV Lights and sunlight, as energy is needed to break the bond homolytically. There can be the homolytic elimination of carbon compounds at high temperature and in the absence of oxygen which is also known as pyrolysis.

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Practise This Question

Which of the following statement is true?