State the trends in the variation of electronegativity in group and periods.

Explanation

Variation of electronegativity in a period: The Variation of Electronegativity along I period electronegativity increases across a period from left to right. Since the atomic radius decreases in a period, the attraction between the valence electron and the nucleus increases. Hence the tendency to attract shared pair of electrons increases. Therefore, electronegativity increases in a period.
Variation of electronegativity in a group: The electronegativity decreases down a group. As we move down a group, the atomic radius increases and the nuclear attractive force on the valence electron decreases. Hence electronegativity decreases in a group.