Question
The reason behind the lower atomic radius of $$Ga$$ as compared to $$Al$$ is
A.
poor screening effect of $$d$$ - electrons for the outer electrons from increased nuclear charge
B.
increased force of attraction of increased nuclear charge on electrons
C.
increased ionisation enthalpy of $$Ga$$ as compared to $$Al$$
D.
anomalous behaviour of $$Ga.$$
Answer :
poor screening effect of $$d$$ - electrons for the outer electrons from increased nuclear charge
Solution :
Presence of 10 $$d$$ - electrons in gallium which have poor screening effect on the outer electrons increases the force of attraction between the outermost electrons and nuclear charge resulting in decrease in atomic radius.