(a) Homologous series: When the members of a hydrocarbon family obey same general formula they are said to be in homologous series.
The members in the series are arranged in increasing order of their molecular masses:
Example:
Alkane – CnH2n+2
CH4 – Methane
C2H6 – Ethane
C3H8 – Propane
C4H10 – Butane
Properties:
- The difference between two consecutive members of homologous series is of – CH2 and mass 14 a.m.u.
- They all show same chemical properties and slight gradation in their physical properties.
(b) IUPAC: International Union of Pure and Applied Chemistry.