Question

What is shilding effect?

Answer 1

Shielding effect is the phenomenon where the valence electrons are shielded from the attraction towards the nucleus. Imagine a beach-ball, inside another beach-ball. The beach balls are negatively charged and held together by a positively charged nucleus at the common center of both beachballs. The force of attraction of the larger beachball towards the center is reduced because of the presence of inner beachball. This is shielding effect.

Shielding effect is pronounced more in the 3d elements. The general trend of elements in the same period is that the atomic radii decreases from left to right. In case of 3d elements, as we move from left to right, electrons are added to the inner 3d orbital which pushes the outer 4s orbital. Thus, the atomic radii is almost constant for these elements.