What changes in the following properties are observed while moving from left to right along a period & from top to bottom in a group? (1) Atomic volume,
(2) Valency,
(3) Electronegativity.

Explanation

(1) On moving from left to right across a period, atomic volume first decreases and then increases. In a group, atomic volume increases with increase in atomic number down a group.
(2) Oxygen-based valency goes on increasing from left to right along a period but does not suffer any change down a group.
(3) Electronegativity increases gradually from left to right across a period while it decreases down a group with increase in atomic number.