Question

Why shielding effect decreases as valence shell is filled?

Answer 1

As valence shells keeps increasing, the distance of valence electrons from nucleus increase which increases atomic radius and hence decrease nuclear force of attraction. Thus, shielding effect due to nuclear attraction decrease

Answer 2

Heya!!!

As the valence shell is filled radius from shell to nucleus increses and hence the nuclear force due to nucleus decreses so shileding effect decreses.

Thanks!!