Question

As one moves down a group from top to bottom, which among the following will not be observed?

• A. Increasing ionisation energy.
• B. Increasing ionic radius.
• C. Decreasing electronegativity.
• D. Increasing atomic radii.

Answer 1

The correct option is A Increasing ionisation energy.

Moving from top to bottom in a group $Z_{eff}$ decreases and we know that:

$I.E.\propto Zeff$
So I.E. also decreases in a group from top to bottom. The electronegativity generally decreases as we go down a group. This is because the atomic radii increases as we go down the group and the nuclear charge is not effectively felt by the outermost electrons and thus the said electrons are not as strongly held comparatively. As we go down a group, since atomic radius increases, we could say that, in general, the ionic radius also increases.