how would you explain lower atomic radius of gallium as compare to alluminium Share with your friends Share 0 Diya answered this due to lanthanoid contraction 1 View Full Answer ...... __ answered this The atomic radius of the Ga is less than Al because of poor screening effect. Theatomic 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. 1