Isomerism is the phenomenon where two or more compounds have the same molecular formula-that is, the same number and types of atoms-but differ in the arrangement of these atoms, resulting in different chemical and physical properties. Compounds exhibiting this phenomenon are called isomers
. There are two primary types of isomerism:
- Structural (or Constitutional) Isomerism: Isomers differ in the connectivity or order in which atoms are bonded together. For example, butane and isobutane both have the formula C4H10 but differ in their carbon chain structure-one is straight, the other branched
- Stereoisomerism: Isomers have the same connectivity but differ in the spatial orientation of atoms. This includes:
- Geometric (cis-trans) isomerism , where groups are arranged differently around a double bond or ring.
- Optical isomerism , where molecules are non-superimposable mirror images (enantiomers) that differ in how they rotate plane-polarized light
In summary, isomerism highlights how molecules with identical atomic compositions can have distinct structures and properties due to differences in atom connectivity or spatial arrangement
