Question

$3 d$-transition series of elements starts with $Sc$ and ends with $Zn$. The electronic configuration of $Sc$ and $Zn$ are respectively.

• A. $[ Ar ] 3 d^{1}\, 4 s^{1}$ and [Ar] $3 d^{10} \, 4 s^{1}$
• B. $[ Ar ] 3 d^{1} \, 4 s^{2}$ and $[ Ar ] 3 d^{10} \, 4 s^{2}$
• C. $[ Ar ] 3 d^{2} \, 4 s^{1}$ and $[ Ar ] 3 d^{9} \, 4 s^{3}$
• D. $[ Ar ] 3 d^{3} \, 4 s^{2}$ and $[ Ar ] 3 d^{8}\, 4 s^{2}$

Answer 1

Answer: (B)

Before the $4 p$-orbital is filled, filling-up of $3 d$-orbitals becomes energetically favourable and we come across $3 d$ transition series of elements. This starts from scandium $(Z=21)$ which has electronic configuration $=[ Ar ] 3 d^{1}\, 4 s^{2}$ and end at zinc $(Z=30)$ with electronic configuration $=[ Ar ] 3 d^{10}, 4 s^{2}$