Question

The reason behind the lower atomic radius of Ga as compared to Al is ?

• A. increased force of attraction of increased nuclear charge on electrons
• B. poor screening effect of d-electrons for the outer electrons from the increased nuclear charge
• C. Anomalous behaviour of Ga
• D. increased ionisation enthalpy of Ga as compared to Al

Answer 1

Answer: (B)

Answer:- (A) poor screening effect of d-electrons for the outer electrons from an increased nuclear charge.

Reason:-

The presence of additional 10d electrons in gallium offers poor screening effect for the outer electrons which increases the force of attraction between the outermost electrons and nuclear charge, due to which the atomic radius of gallium decreases.

Hence, Ga has a lower atomic radius as compared to Al.