A series of organic compounds having similar structures and similar chemical properties in which the successive members differ in their molecular formula by -CH2 group.
The different members of the series are called homologous.
Characteristics of Homologous Series
All the member of a homologous series can be described by a common general formula.
Example: All alkane can be described by the general formula CnH2n+2.
Each member of a homologous series differ from its higher and lower neighbouring members by a common difference of -CH2 group.