What is the Difference Between Homolytic and Heterolytic Fission?

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Homolytic and heterolytic fission are two different ways in which a covalent bond can be broken. The main differences between them are:

  1. Bond breaking: Homolytic fission occurs when the covalent bond breaks evenly, and each of the bonded atoms takes one of the shared pair of electrons from the bond. In contrast, heterolytic fission occurs when the covalent bond breaks unevenly, and one of the bonded atoms takes both of the electrons from the bond.
  2. Electron distribution: In homolytic fission, the bonded pair of electrons is distributed evenly between the two atoms, resulting in the formation of atoms with a single unpaired electron. In heterolytic fission, the bonded pair of electrons goes to a single atom, resulting in the formation of ions with opposite charges.
  3. Conditions: Homolytic fission requires a high amount of energy to break the bond equally, while heterolytic fission occurs under different conditions.

Examples of homolytic fission include reactions in the presence of ultraviolet radiations, such as the breaking of a chlorine molecule. Heterolytic fission takes place in the breaking of a bond in hydrochloric acid.

Comparative Table: Homolytic vs Heterolytic Fission

Here is a table summarizing the differences between homolytic and heterolytic fission:

Homolytic Fission Heterolytic Fission
Breaking of bond in which one electron is transferred to each fragment Unequal breaking of the covalent bond resulting in the formation of a positive and negative ion
Results in the formation of free radicals Results in the formation of cations and anions
Occurs in compounds in which the atoms have the same or very less electronegativity difference Takes place in compounds with polar characters or which have atoms with a high electronegativity difference
Non-polar solvents and high temperatures favor this type of bond fission Polar solvents and low temperatures favor this type of bond fission

In homolytic fission, a chemical bond is broken in such a way that each of the original fragments retains one electron, resulting in the formation of free radicals. This process occurs in compounds where the atoms have similar electronegativity values and is favored by non-polar solvents and high temperatures.

In heterolytic fission, a chemical bond is broken unevenly, resulting in the formation of cations and anions. This process takes place in compounds with polar characters or atoms with high electronegativity differences and is favored by polar solvents and low temperatures.