What is Actinoid contraction ? Explain it.

Explanation

The steady decrease in atomic and ionic radii of the elements of actinoid series from left to right is called actinoid contraction. As we move from left to right in the Actinoid series, the nuclear charge increases. This is compensated by shielding effect of f-electrons. But f-electrons have poor shielding effect. It means in crease in nuclear charge is not overcome by shielding effect. Hence atomic and ionic radii decreases which leads to actinoid contraction.