What is meant by isomerism and what are the types of isomerism?

Answer 1

Isomerism is the phenomenon in which two or more compounds have same molecular formula but their structural formula is different. The compounds are called Isomers.

There are 2 types of isomerism.

1) Structural Isomerism which is further classied into 5 more types of isomerisms:

i) Chain Isomerism which is due to difference in nature or the carbon chain e.g. isopentane, neopentane or n-pentane

ii) Position isomerism which is due to the difference in position of the functional group or unsaturated linkage in the same carbon chain. e.g. 1-Chloropropane is the isomer or 2-chloropropane or another example is 1-butene which is isomer of 2-butene

iii) Functional group isomerism in which there are different functional group but same molecular formula. e.g. dimethyl ether is functional group isomer of ethyl alcohol

iv) Metamerism is due to the unequal distribution of carbon atoms on either side of the functional group and such compounds belong to same homologous series. e.g. diethyl ether and methyl n-propyl ether are metamers.

dietheyl ether: CH3 - CH2 - O - CH2 - CH3

methyl n-propyl: CH3 - O - CH2 - CH2 - CH3

v) Tautomerism due to shifting of proton from one atom to other in the same molecule.

The 2nd type of isomerism is Cis-trans Isomerism or geometric isomerism and compounds who possess same structural formula but differ with respect to the positions of the identical groups in space are called cis-trans isomers and the phenomenon is cis-trans or geometric isomerism.

Answer 2

Isomerism is when molecules have the same molecular formula but different structural arrangements or spatial orientation of atoms. The main types of isomerism are structural isomerism (different connectivity of atoms), stereoisomerism (same connectivity but different spatial arrangement), and conformational isomerism (different arrangements due to rotation around single bonds).