What is a homologous series ? Explain with an example.

Explanation

A homologous series is a group of organic compounds having similar structures and similar chemical properties in which the successive compounds differ by `CH_(2)` group. The various organic compounds of a homologous series are called homologues. All the homologues of a series contain the same functional group. An example of homologous series is given below.
The compounds called alcohols form a homologous series. Methanol `CH_(3)OH`, ethanol `C_(2)H_(5)OH` propanol `C_(3)H_(7)OH` an dbutanol `C_(4)H_(9)OH` are the first for members of the homologous series of alcohols:
Methanol `CH_(3)OH`
Ethanol `C_(2)H_(5)OH`
Propanol `C_(3)H_(7)OH`
Butanol `C_(4)H_(9)OH`
All these alcohols have similar structures having the same functional group (alcohol group : `-OH` ) and show similar chemical properties. The formulae of the successive members of this homologous series of alcohols differ from each other by `CH_(2)` group (1 carbon atom and 2 hydrogen atoms). If we calculate the molecular masses of the above memebrs of the homologous series of alcohols, we will find what they differ from each other by 14 u.