Question

The effect of lanthanide contraction in the lanthanide series of elements by and large means:
(A) Decrease in both atomic and ionic radii
(B) Increase in atomic radii and decrease in ionic radii
(C) Increase in both atomic and ionic radii
(D) Decrease in atomic radii and increase in ionic radii

Answer 1

Hint: The solubility product is the equilibrium constant for saturated solutions of Ionic compounds. The units of solubility products depend upon the stoichiometric coefficients of concentration terms.

Complete step by step answer: To know about lanthanide contraction we need to know about the shielding effect. Shielding effect is also known as the atomic shielding describes the attraction existing between the nucleus and an electron. More the electron density in an orbital more is the shielding effect. Higher the inner electrons higher will be a shielding effect. The trend is given as follows: ‘s’ subshell has more shielding effect than ‘f’ subshell.

$s< p < d < f$
The reason behind this is that the ‘s’ subshell electrons are near to the nucleus thus has greater electron density in the nucleus hence greater shielding effect. It is also described as the condition where the inner shell electrons shield the outer shell electrons thereby reducing their effect on nuclear charge. When this shielding effect is low it means the outer shell electrons will have greater attraction for the nuclear thus reducing the distance between the outer electron and the nucleus. Thereby, the atomic and ionic radius decreases.
Since lanthanide elements are having ‘f’ subshell electrons these electrons have the lowest shielding effect. Thus, the atomic and ionic decreases. This phenomenon is known as lanthanoid contraction.
Due to lanthanide contraction in the lanthanide series of elements there is a decrease in both atomic and ionic radii. So, the correct option is A.

Note: Due to lanthanoid contraction, there is a similar radii observed between the 3d and 4f block elements. Moreover, the exceptions in electronic configuration is also due to the lanthanoid contraction.