1. it is defined as the change in the polarization of a covalent bond due to the presence of adjacent bonded atoms or groups in the molecule. It is denoted as 1 effect.
2. Atoms or groups which lose electron towards a carbon atom are said to have a \(-1\) effect.
Example: \(\mathrm{CH}_{3}:\left(\mathrm{CH}_{3}\right)_{2} \mathrm{CH}-\left(\mathrm{CH}_{3}\right)_{2} \mathrm{C}\) - etc.
3. Atoms or groups which draw electrons away from a carbon atom are said to have a -l effect.
Example: \(-\mathrm{NO}_{2} \cdot-1,-\mathrm{Br}_{r}-\mathrm{OH}, \mathrm{C}_{6} \mathrm{H}_{5}\) etc.
4. For example, consider ethane and ethyl chloride. The \(c \cdot c\) bond in ethane is non polar while the C-C bond in ethyl chloride is polar. We know that chlorine is more electronegative than carbon and hence it attracts the shared pair of electrons between \(C-C l\) in ethyl chloride towards it self.
This develops a slight negative charge on chlorine and a slight positive charge on carbon to which chlorine is attached. To compensate it, the \(C_{1}\) draws the shared pair of electron between itself and \(C_{2}\). This polarization effect is called inductive effect.
