Question
The increasing order of atomic radii of the following Group 13 elements is
A.
$$A\ell < Ga < In < T\ell $$
B.
$$Ga < A\ell < In < T\ell $$
C.
$$A\ell < In < Ga < T\ell $$
D.
$$A\ell < Ga < T\ell < In$$
Answer :
$$Ga < A\ell < In < T\ell $$
Solution :
Atomic radii increases on moving down a group. However due to poor shielding effect of $$d$$ orbit, atomic radius of $$Ga\,$$ is smaller than $$Al$$ (anomaly). Thus the correct order is $$Ga < A\ell < In < T\ell $$