Question

What is called homologous series? Give any three of its characteristics?

Answer 1

A homologous series is a group or a class of organic compounds having the same general formula and similar chemical properties in which the successive members differ by a -CH₂ group.

Characteristics of homologous series:

1. Each member of the series differs from the proceeding or succeeding member by one methylene group (-CH₂) and hence by a molecular mass of 14 amu.
2. All members of a homologous series contain the same elements and functional group.
3. They are represented by a general molecular formula. Eg: Alkanes, C₂H_2n+2.
4. The members in each homologous series show a regular gradation in their physical properties with respect to their increase in molecular mass.
5. The chemical properties of the members of a homologous series are similar.
6. All the members can be prepared by a common method.