The existence of two or more compounds with the same molecular formula but different properties (physical, chemical or both) is known as isomerism; and the compounds themselves are called isomers. The term was given by Berzelius. The difference in properties of the two isomers is due to the difference in the arrangement of atoms within their molecules.
Isomerism may be of two types:
Structural isomerism and
Stereoisomerism.
