. Why homologous series of carbon compounds are so called

Write chemical formula of two consecutive members of a homologous series and state the part of these compounds that determines their (i) physical properties, and (ii) chemical properties.                   


Best Answer

Ans. All the organic compounds having similar structures show similar properties and they are put together in the same groups or series called homologous  series.

 For example,  all the alkanes  have similar structures  with single covalent  bonds  and show  similar  chemical  properties  so  they  are  grouped   together  in  a homologous series having general formula CnH2n+2 .

• The two consecutive  members of a homologous  series are methane CH4  and ethane


(i) Any two adjacent homologues differ by 1carbon and 2 hydrogen atoms in their molecular formulae. So the difference in molecular masses of any two adjacent homologues is 14 u. Thus the members of a homologous series show a gradual change in their physical properties with increase in molecular mass.

(ii) All the compounds of a homologous series show similar chemical properties because they have similar structures and similar bonding.


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