JEE Advanced · 2016 · 22 May 2016 · Paper 1 · p-Block Elements

The increasing order of atomic radii of the following Group 13 elements is

(A) $Al < Ga < In < Tl$
(B) $Ga < Al < In < Tl$ ✓ Correct
(C) $Al < In < Ga < Tl$
(D) $Al < Ga < Tl <$ In

Answer: (B)

Solution

In Group 13, the atomic radius generally increases down the group. However, Ga has a smaller radius than Al due to the poor shielding effect of the filled 3d electrons, which increases the effective nuclear charge experienced by the valence electrons. Thus, the correct order is

Ga < Al < In < Tl

JEE Advanced · 2016 · 22 May 2016 · Paper 1 · Single correct option

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