PrepZii

table

Structure Isomerism Comparison

The source table classifies five kinds of structural isomerism and gives the key condition for each.

Type	What changes	What remains same	Key condition
Chain isomerism	Size of main chain or side chain	Nature of locants	Same nature of locants.
Positional isomerism	Position of locants	Size of main/side chain and nature of locant	Same size of main chain and side chain.
Functional isomerism	Nature of locant	Molecular formula	Chain and positional isomerism are not considered.
Metamerism	Nature of alkyl groups around polyvalent functional group	Nature of functional group	Chain and positional isomerism are ignored.
Tautomerism	Position of hydrogen atom	Two functional-isomer forms	Two functional isomers remain in dynamic equilibrium.