Question -
Answer -
When two dissimilar atomshaving different electronegativities combine to form a covalent bond, the bondpair of electrons is not shared equally. The bond pair shifts towards thenucleus of the atom having greater electronegativity. As a result, electrondistribution gets distorted and the electron cloud is displaced towards theelectronegative atom.
As a result, theelectronegative atom becomes slightly negatively charged while the other atombecomes slightly positively charged. Thus, opposite poles are developed in themolecule and this type of a bond is called a polar covalent bond.
HCl, for example, containsa polar covalent bond. Chlorine atom is more electronegative than hydrogenatom. Hence, the bond pair lies towards chlorine and therefore, it acquires apartial negative charge.
