Question

What do you mean by lanthanide contraction? Explain in detail.

Answer 1

The lanthanide contraction is the greater-than-expected decrease in ionic radii of the elements in thelanthanide series from atomic number 57, lanthanum, to 71, lutetium, which results in smaller than otherwise expected ionic radii for the subsequent elements starting with 72, hafnium.
The Lanthanide Contraction is caused by a poor shielding effect of the 4f electrons. Gd because as atomic number increases, the atomic radius decreases. Yb because it has a larger atomic number. Because the elements in Row 3 have 4f electrons.

Answer 2

they are separated from the periodic table with actinoids...haha might be