Question

What is the general electronic configuration for ${2^{nd}}$ row transition series?
A.$\left[ {Ne} \right]3{d^{1 - 10}},4{s^2}$
B.$\left[ {Ar} \right]3{d^{1 - 10}},4{s^{1 - 2}}$
C.$\left[ {Kr} \right]4{d^{1 - 10}},5{s^{1 - 2}}$
D.$\left[ {Xe} \right]5{s^{1 - 10}},5{s^{1 - 2}}$

Answer 1

Chemical elements in the periodic table are arranged in blocks. d-block is the middle block consisting of transition elements and non-transition elements. There are three rows in transition elements. The second-row elements configuration can be written by writing the krypton and valence electrons.

Complete answer: Chemical elements were represented in the periodic table. In the periodic table the chemical elements were arranged in the increasing order of atomic numbers and arranged in vertical columns and horizontal rows. The vertical columns were known as groups and the horizontal rows are known as periods. These elements were divided into s, p, d and f blocks. The d-block elements are transition and non-transition elements.
The d-block elements are divided into three series namely $3d,4d$ and $5d$ series. The transition elements are the d-block elements in which the shells are not completely filled. The d-block elements in which the shells are completely filled are known as non-transition elements.
The second-row transition elements start from the atomic number Yttrium $\left( {39} \right)$ to silver $\left( {47} \right)$ . Thus, the general electronic configuration for ${2^{nd}}$ row transition series $\left[ {Kr} \right]4{d^{1 - 10}},5{s^{1 - 2}}$. As, krypton is the nearest noble gas to the second-row transition series. The last electron enters into the d-orbital.
Hence the correct option is (C).

Note:
Krypton is a noble gas with atomic number $36$ , it is the nearest inert gas to the second-row transition chemical elements. Thus, it should be written. Silver is a chemical element which has a completely filled d-orbital but not completely filled s-orbital, and it is the last transition element in the second row.