Question

Element having electronic configuration $1{s^2},2{s^2},2{p^6},3{s^2},3{p^6},3{d^{10}},4{s^2},4{p^6},4{d^{10}},5{s^2},5{p^{3}}$ belongs to the group in the periodic table:
A) ${3^{rd}}A{\text{ }}group$
B) ${2^{nd}}A{\text{ }}group$
C) ${5^{th}}A{\text{ }}group$
D) ${7^{th}}A{\text{ }}group$

Answer 1

The concept of this question belongs to the modern periodic table and electronic configuration, as electronic configuration can describe how the electrons are arranged within the orbital shells and subshells of an atom. We know that in the periodic table sequencing of elements is done on the basis of their atomic number, as they are categorized according to their properties.

Complete step by step answer:

1. From the concept we know that group number is always similar to the number of valence electrons of the given element. First, we will write the given electronic configuration of the element as below,
   Electronic Configuration: $1{s^2},2{s^2},2{p^6},3{s^2},3{p^6},3{d^{10}},4{s^2},4{p^6},4{d^{10}},5{s^2},5{p^{3}}$
2. Since the last electron enters in p – subshell. The last block will be ′p′.
3. For the group we have the element in p-block ${\text{Group number = 10 + Valence electron in s Subshell + Valence Electron Subshell}}$
   ${\text{Group Number = 10 + 2 + 3 = 15 i}} \cdot {\text{e}} \cdot {\text{ 1}}{{\text{5}}^{{\text{th}}}}{\text{group or}}{{\text{5}}^{{\text{th}}}}{\text{Agroup}}$
   Therefore, the element having electronic configuration belongs to the ${5^{th}}A{\text{ }}group$ in periodic table which shows option C as the correct choice.

Additional information: To predict electronic configuration, divide the periodic table into sections to predict the atomic orbital, the regions where electrons are contained. Group one and two represent the S block, three through ${\text{12}}$ represents the d-block and ${\text{13 to 18}}$are the p-block and the last two rows at the bottom are f –block.
For s block elements: ${\text{Group Number = Number of valence electron}}$
For d block elements:
${\text{Group Number = Number of electrons in}}\left( {{\text{n - 1}}} \right){\text{d'subshell + number of electrons in}}{{\text{n}}^{{\text{th}}}}{\text{subshell}}$
For f-block elements: ${\text{Group Number = 3}}\left( {{\text{always}}} \right)$

Note:
The modern periodic table based on atomic number as it considers as the fundamental property and element are arranged based on their increasing atomic numbers and isotopes are kept at the same spot in the periodic table due to their atomic numbers being the same.