CBSE Class 10 Answered

The tendency of an atom in a molecule to attract the shared pair of electrons towards itself is called its electronegativity.

Electronegativity of elements gradually decreases from top to bottom in a group.

Reason: Down a group there is an increase in atomic number due to the addition of extra shells, the atomic size increases. The effect of an increase in the atomic size overcomes the effect of an increase in the nuclear charge.

Electronegativity of elements in­creases in going from left to right across the period.

Reason:Since the nuclear charge increases due to an increase in atomic number.