CARBON COMPOUNDS PART-3

Homologous series :

  • Any family of compounds in which adjacent members differ from each other by a definite factor (CH2 group) is called a homologous series. 

Characteristics of homologous series :

  • Any 2 consecutive members differ in their formula by a common difference of -CH2.
  • Different members have common functional group.
  • Members of any particular family have almost identical chemical properties.
  • Their physical properties show gradual gradation with increase in the molecular mass.
  • Members differ by molecular mass of 14.

 

Functional group

  • In hydrocarbon chain, one or more hydrogen atom is replaced by other atoms in accordance with their valancies. These are heteroatom.
  • These heteroatom or group of atoms which make carbon compound reactive and decides its properties are called functional groups.

 

Nomenclature of Organic Compounds

  • A prefix to the name comes before the molecule.
  • The prefix of the molecule's name is based on the number of carbon atoms.
  • For example, a chain of six carbon atoms would be named using the prefix hex-. 

Prefix

Number of
 Carbon atoms

Formula

meth-

1

C

eth-

2

C2

prop-

3

C3

but-

4

C4

pent-

5

C5

hex-

6

C6

hept-

7

C7

oct-

8

C8

non-

9

C9

dec-

10

C10

 

  • The suffix or ending of the name of a hydrocarbon depends on the nature of the chemical bonds between the carbon atoms.
  • The suffix is -ane if all of the carbon-carbon bonds are single bonds, -ene if at least one carbon-carbon bond is a double bond , and -yne if there is at least one carbon-carbon triple bond .