Question

In my Pearson book it is written that Atmoic radius decreases due to increase in atomic number

Also

Ionization energy increases from top to bottom of a group since the atomic size decreases due to increase in atomic number

Please explain sir

Answer 1

Down a group, atomic radius increases.

The valence electrons occupy higher levels due to the increasing quantum number (n).
As a result, the valence electrons are further away from the nucleus as ‘n’ increases.
Electron shielding prevents these outer electrons from being attracted to the nucleus; thus, they are loosely held, and the resulting atomic radius is large.

Also ionization energy decreases down a group ,( but ionization energy increases as we go across the period ,left to right)

The first ionisation energy decreases on going down a group.
This is because the electron to be removed from the outer energy level is increasingly distant from the nucleus, as a result of the atoms getting bigger.
The attraction of the nucleus for the electron becomes less, and it becomes easier to pull it away

Ionization Energy
The ionization energy is qualitatively defined as the minimum amount of energy required to remove the most loosely bound electron, the valence electron, of an isolated neutral gaseous atom to form a cation