Question
What are non-polar and polar covalent bonds? Give examples.
Solution
(i) Non-polar covalent bond. If a covalent bond is formed between two identical atoms, the shared pair of electrons is attracted equally by both the atoms and lies exactly midway between them, such a bond is called a non-polar covalent bond. For example, in a molecule of H2 or Cl2, the shared pair of electrons is attracted equally between the two hydrogen atoms or chlorine atoms and hence the resulting bond is non-polar.
(ii) Polar covalent bond. If a covalent bond is formed between two dissimilar (non-identical) atoms having different electronegativities, the shared pair of electrons is pulled closer towards more electronegative atom, such a bond is called the polar covalent bond. The more electronegative atom acquires partial negative charge (δ–) while less electronegative atom acquires a partial positive charge (δ+). For example, hydrogen fluoride molecule has a polar covalent bond.
Other molecules having polar covalent are H-Cl, H2O and NH3.
(ii) Polar covalent bond. If a covalent bond is formed between two dissimilar (non-identical) atoms having different electronegativities, the shared pair of electrons is pulled closer towards more electronegative atom, such a bond is called the polar covalent bond. The more electronegative atom acquires partial negative charge (δ–) while less electronegative atom acquires a partial positive charge (δ+). For example, hydrogen fluoride molecule has a polar covalent bond.
Other molecules having polar covalent are H-Cl, H2O and NH3.
