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.

Answer:

  (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.