Question

The outer electronic configuration of group ${\text{V A}}$ elements is:
A.$n{s^2}n{p^2}$
B.$n{s^2}n{p^3}$
C.$n{s^2}n{p^4}$
D.$n{s^2}n{p^5}$

Answer 1

Aufbau principle: In this principle, atomic orbitals which have lowest energy are filled first after that the orbitals with high energies are filled.
Pauli’s exclusion principle: It states that for any electrons the values of all the four quantum numbers cannot be the same. They differ in at least one quantum number.

Complete step by step answer:
The elements of group $15$ are known as group ${\text{V A}}$ elements. They have $5$ electrons in their valence shell so the general electronic configuration of group ${\text{V A}}$ elements is as $n{s^2}n{p^3}$ where $n$ is the periodic number. For example: nitrogen the first element of this group has electronic configuration as: $2{s^2}2{p^3}$ because this is the $2$ period element.

Hence option B is correct.

Additional information:
Now Let us talk about quantum numbers.
Quantum number: It is defined as the set of numbers which describes the position and energy of electrons in an atom. There are four quantum numbers: principal, azimuthal, magnetic and spin quantum numbers.
Principle quantum number: It is defined as the quantum number which describes the electron’s state. It is represented by $n$. It’s value starts from $1$.
Azimuthal quantum number: It is defined as a quantum number which describes the shape of the orbital and its orbital angular momentum. It is represented by $l$. It’s value is from $0$to $(n - 1)$.For $s$ $l = 0$for $p{\text{ l}} = 1$ and so on.
Magnetic quantum number: It is defined as the quantum number which describes the orientation in shape of orbitals. It is represented by $m$. Its value is from $- l$to $l$. They generally represent the subshell of the orbitals. For example: For s shell $l = 0$. So the value of $m = 0$. Hence there is only a subshell for s-shell. Similarly for p shell $l = 1$. So the value of $m$can be $- 1,0,1$. Hence there will be three subshells for the p-shell. In general the number of subshells is equal to $2l + 1$.
Spin quantum number: It describes the angular momentum of the electron. Spin quantum numbers have two values $+ \dfrac{1}{2}$or $- \dfrac{1}{2}$.At a time electrons can have one spin value.
Degenerate orbitals: Those orbitals of the same subshell which have the same energies, are known as degenerate orbitals. For example: In $2p$ shell there are three subshells as $2{p_x},2{p_y},2{p_z}$. They have the same energy. So we can say that degenerate orbitals have the same principal quantum number and azimuthal quantum number.

Note:
For d-shell there are five subshells as the value of azimuthal quantum number $l$ is $2$. So total number of magnetic quantum numbers i.e. $m = 2l + 1 = 5$. They are as: ${d_{xy}},{d_{yz}},{d_{xz}},{d_{{x^2} - {y^2}}},{d_{{z^2}}}$. They all have the same principal and azimuthal quantum number but have different magnetic and spin quantum numbers.