Question

What is the total number of unpaired electrons in \[M{n^{2 + }}\] ion?

Answer 1

Hint: Manganese is a naturally occurring mineral having an atomic number of 25 and the symbol Mn. It is the fifth most abundant metal found in the Earth's crust. The number of unpaired electrons in manganese can be found with the help of its electronic configuration. In the electronic configuration, the electrons are needed to be filled in the shells in accordance with Afbau’s principle.

Complete Step by Step Solution:
According to Aufbau's principle, the electrons need to be arranged according to the increasing energy of the subshells.

The increasing order of subshells based on their energy is:-
1s< 2s <2p< 3s <3p <4s <3d< 4p <5s< 4d <5p <6s< 4f< 5d <6p<7s<5f<6d<7p
Thus, the electronic configuration of Manganese as a neutral atom, i.e. Mn is:-
Mn: \[1{s^2}2{s^2}2{p^6}3{s^2}3{p^6}3{d^5}4{s^2}\]
As, the question has asked for \[M{n^{2 + }}\] ion, i.e. Mn with 25 – 2 = 23 electrons, the electronic configuration becomes,
Mn²⁺: \[1{s^2}2{s^2}2{p^6}3{s^2}3{p^6}3{d^5}\]
From the last subshell, i.e. 3d, it is evident that \[M{n^{2 + }}\] ion has 5 unpaired electrons.

Note: An atomic orbital is a mathematical function, it provides insight into the wave nature of the electrons that exist around the nuclei of atoms. These mathematical functions are often used in order to determine the probability of finding an electron in a specific region around the nucleus of the atom. While filling up the orbitals with electrons, one should always remember to fill up the orbitals according to their energy levels. Before pairing up electrons in an orbital, all the orbitals must have at least one electron.