Izoizomerism

Izomerism is a phenomenon in chemistry where two or more chemical compounds have the same molecular formula but differ in the structural arrangement of their atoms. These different compounds, called isomers, exhibit distinct physical and chemical properties. The term "isomer" comes from the Greek words "isos" meaning equal and "meros" meaning part.

There are two main categories of isomers: structural isomers and stereoisomers. Structural isomers, also known as constitutional isomers, have the same molecular formula but differ in the connectivity of their atoms. This means the atoms are linked in a different order. For example, butane and isobutane (or 2-methylpropane) both have the molecular formula C4H10 but are structural isomers due to their different carbon chain arrangements.

Stereoisomers, on the other hand, have the same molecular formula and the same connectivity of atoms but differ in the three-dimensional orientation of their atoms in space. This category includes enantiomers, which are non-superimposable mirror images of each other, and diastereomers, which are stereoisomers that are not mirror images. Geometric isomers, a type of diastereomer, arise from restricted rotation around a bond, often in alkenes or cyclic compounds, leading to different spatial arrangements of substituents. The concept of isomerism is fundamental to understanding the diversity and behavior of chemical substances.