Question

Which ion is paramagnetic in nature?

Answer 1

Hint : The ions which have paired electrons and due to which the spins of electrons get cancelled because of each other are known as diamagnetic ions. These ions repel the magnetic field. While, the ions which have unpaired electrons in its orbitals and have some net amount of magnetic moment then we call them paramagnetic ions.

Complete Step By Step Answer:
We know that the electrons in the atomic orbitals are filled according to some rules and out of them one such rule is Pauli Exclusion Principle which states that the two electrons present in a single orbital should have opposite spins and other rule is Hund’s rule which states that the electron pairing in orbitals should be done after all the orbitals have been singly occupied first.
So, when the atomic orbital of an atom is filled with two electrons, the electronic spins of the electrons are opposite to each other and cancel out each other’s spin and hence are diamagnetic in nature. While the ions in whose orbitals single or unpaired electrons are present, so there will be some net magnetic moment and hence, the ion will be paramagnetic in nature.
If we take the example of divalent ion of manganese, $M{n^{2 + }}$ :
Its electronic configuration is: $$ 1{s^2}2{s^2}2{p^6}3{s^2}3{p^6}3{d^5} $$
Hence, we can see that the five orbitals in the $3d$ are first singly filled and there are $5$ unpaired electrons present in it. There will be some net magnetic moment due to these unpaired electrons.
Hence, $M{n^{2 + }}$ ion is paramagnetic in nature.

Note :
We should remember that the orbitals should be filled with electrons according to the Aufbau principle which states that the orbital with lower energy should be filled before the orbital with higher energy. That is why the $4s$ Orbital is filled before the $3d$ orbital. But the electrons are always removed from the outermost shell or orbital which is $4s$ .