Homologous series and characteristics of homologous series
Series of organic compounds which have same functional group, similar structural feature but differ from each other by integer number of CH2(methylene group) is called “Homologous series”. The number of homologous series differs by molecular mass 14.
Characteristics of Homologous series:
1. All numbers of homologous series have similar structures.
2. Physical properties of homologous series change progressively more than or less than with the number of carbon atoms.
3. The members of homologous series are represented by same general formula CnH2n+2 for alkane ,CnH2n for alkene and CnH2n-2 for alkyne.
4. The molecular formula difference between any two consecutive members is CH2.
5. The molecular weight differences between any two successive members is 14.
6. The various members of homologous series have same general method of preparation.for example all alkanes can be prepared by the reduction of alkyl halide.
7. The various members of homologous series show regular graduations in physical properties and have same chemical properties.
8. The name of the member of a homologous series either end with same suffix or start with same prefix.