Question

atomic radius of Ga is less as compared to Al.Why?​

Answer 1

The atomic radius of the Ga is less than Al because of poor screening effect. The atomic radius of Ga is slightly lesser than of Al because in going from Al to Ga, the electrons have already occupied 3d sub shell in Ga.

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Answer 2

these are a part of same grp 13 ( b,al,ga,in,tl)
◇cause the radius of atom decreases when down down to grp
and this is due to following reason:-
● the electrons becomes more and more when goes down to grp so that there shells increases wid same electrons in its valance shell, so that electrostatic force of attraction becomes less and less due to this atomic radius increases.