• # question_answer 85) Give reasons for the following : (a) Covalent bonds are directional bonds while ionic bonds are non-directional. (b) Water molecule has bent structure whereas carbondioxide molecule is linear. (c) Ethyne molecule is linear.

(a) In a covalent bond, the overlapping between half filled atomic orbitals which have definite directions takes place i.e., shared electron pair/pairs are localized between two atoms. Thus, covalent bond is known as a directional bond. In ionic compounds, each ion has its influence in all directions, hence it is surrounded by a number of oppositely charged ions with no definite direction. (b) In water, the central oxygen atom is $s{{p}^{3}}$?hybridised whereas in$C{{O}_{2}}$, the central carbon atom is$sp$-hybridised. Net dipole moment of$C{{O}_{2}}$  is zero whereas ${{H}_{2}}O$has a considerable value. This shows $C{{O}_{2}}$is linear whereas water has bent structure. (c) In ethyne, each carbon atom is sp-hybridised  giving a linear structure.