Structural Isomerism

Structural Isomerism


Structural isomers are those isomers in which the atoms are completely arranged in a different order with the same molecular formulas.

These are the molecules having the same kind of molecular formula with different connectivities depending upon the order they are put together. The structure of Alkane (C4H10) is one of the simple examples representing a structural isomer with different isomers. With the increase in the number of Carbon atoms in the alkane molecule, the structural isomers increase.

Structural Isomerism

The isomers differing in the atomic arrangement of the molecules without any kind of reference to the spatial arrangement are known as the structural isomers. The phenomenon of this structural isomers is called as structural isomerism.

The Structural isomerism is also called as constitutional isomerism as per the IUPAC. It is kind of isomerism where the molecules having the same molecular formula with different orders and bondings, as opposed to that of the stereoisomerism.

Read More: Isomers and Isomerism

Types of Structural Isomerism

There are three types of Structural isomerism existing namely chain isomerism, position isomerism and functional group isomerism.

  • Chain Isomerism: Chain isomerism occurs when there is a difference in the atomic arrangement of the carbon to the carbon chain of a molecule. If two or more compounds having the same type of molecular formula with different main chains, then they are said to exhibit the property of Chain isomerism. This phenomenon is also called as skeletal isomerism.
  • Position Isomerism: Positional isomerism arises when there is a difference in the positions occupied by the substituent atoms or a group of atoms or due to the unsaturation occurring in the chain. When the position of the functional groups with respect to main chain atom changes, the phenomenon is called as position isomerism.
  • Functional Group Isomerism: The Functional group isomerism occurs when there is a  presence of the odd form of functional groups with the same chemical formula. When some compound has two different structures but the same chemical formula, then it is said to exhibit functional isomerism.


Free Class