Iductive effect

INDUCTIVE EFFECT
The polarization of a bond induced by an adjacent polar bond through movement of sigma electrons is called inductive effect.
Reason:
The inductive effect refers to the polarity produced in a molecule as a result of higher electronegativity of one atom as compared to another.

 ʆʆ+  ʆ+    ʆ-

CH3CH2Cl

      Chloroethane

Another example is of ethyle trialkyle ammonium cation.

ʆʆ +    ʆ+        +

CH3   CH2   NR3

Inductive effect can operate in opposite direction depending upon nature of functional groups.For example 

 ʆʆ-     ʆ-        -

CH3  CH2   O

The functional groups responsible for producing inductive effect can be classified as

1.Electron withdrawing groups (-I)
2.Electron donating groups (+I)