Question

Polar covalent Bond exists between atoms of:

• A. Metal and a Non metal
• B. Different element
• C. Different elements whose electronegativity difference is high
• D. Different elements whose electronegativity difference is less

Answer 1

The correct option is C Different elements whose electronegativity difference is high

A polar covalent bond exists between atoms of different elements whose electronegativity difference is high. The bond between two unlike atoms, which differ in their affinities for electrons is said to be a polar covalent bond. When a covalent bond is formed between two atoms of different elements, the bonding pair of electrons will lie more towards the atom, which has more affinity for electrons. As the said electron pair do not lie exactly midway between the two atoms, the atom with higher affinity for electrons develops a slightly negative charge and the atom with a lesser affinity for electrons, a slight positive charge. Such molecules are called 'polar molecules'.In the hydrogen chloride $\left(HCl\right)$ molecule, the bonding of hydrogen and chlorine atoms lies more towards $Cl$ atom (because $Cl$ is more electronegative) in the shared pair of electrons. Therefore, $Cl$ atom acquires a slight negative charge, and $H$ atom a slight positive charge. This causes the covalent bond between $H$ and $Cl$ to have an appreciable ionic character.
Hence option $C$ is correct.