3.0 Homologous series

  General Organic Chemistry

• A series of compounds in which the various members have similar structural features, similar chemical properties and the successive members differ in their molecular formula by $CH_2$ is known as homologous series.
  
  
• The individual members of homologous series are called homologues.
  
  
• All compounds of the series can be represented by one general formula.

• The molecular mass of every two adjacent members differs by 14.
  
  
• Different members in a series have a common functional group. For example, the members of the alcohol family have $-OH$ group as their functional group.
  
  
• The members in any particular family have almost identical chemical properties. Their physical properties such as melting point, boiling point, density, solubility etc show a general graduation with the increase in the molecular mass.
  
  
• The members of a particular series can be prepared almost by the identical methods, known as the general method of preparation.