Q. Identify the correct order in which the covalent radius of the following elements increases (I)Ti (II) Ca (III) Sc
A) (I), (II), (III)
B) (III), (II), (I)
C) (II), (I), (III)
D) (I), (III), (II)
Explanation
(d)
$\ _{20}Ca = \lbrack Ar\rbrack 4s^{2}$
$\ \ _{21}Sc = \lbrack Ar\rbrack 4s^{2},3d^{1}\$
$\ _{22}Ti = \lbrack Ar\rbrack 4s^{2},3d^{2}$
As $d$-orbital have diffused shape, hence their electron shields nuclear charge upto lesser extent. Hence, due to increase in effective nuclear charge $(Z_{eff})$ atomic size decrease, in the following order
$Ca > Sc > Ti$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.