Question

State Hund’s rule of maximum multiplicity.

Answer 1

Hint: We must know that the Hund’s rule states about electron filling in an orbitals. And Hund’s rule solves the drawbacks of the Aufbau principle of chemistry.


Complete step by step solution:
As you guys must be aware of the Aufbau principle of chemistry which states that electrons are filled first in the energy orbital having the lowest amount of energy. And followed by the complete filling of these orbital the electrons are filled in the orbital with higher energy.
But there is a shortcoming in Aufbau principle of chemistry, the shortcoming is that this rule doesn’t tell us about the three 2p orbitals and their filling. For solving this problem Hund’s rule of maximum multiplicity was stated.
So, basically what Hund’s rule stated was that:
Any orbital cannot be double filled until the sub-level of the energy orbital is singly occupied.
The single-occupancy orbital having the same spin is the necessary condition for the maximization of the total spin.
Well, Hund’s rule for maximum multiplicity states that for a known electronic configuration, the greatest value of spin multiplicity holds the lowest energy term.
Or
To say it in another way this rule states that ‘for a known electronic configuration, the term which has maximum multiplicity falls under the lowest energy category’.
According to this rule p, d, and f orbitals cannot be filled until and unless each orbital of a particular subshell is singly occupied or contains one electron in it.
Each subshell carries 2 electrons, so in case of p orbital there are 3 such subshells. So when filling these subshells first only one-one electron enters each subshell, only after each subshell is half filled the second electron enters the subshell.



Note: We must know that the Hund’s rule is applicable for finding the stability of an atom as well as the ionization potential of an atom. It helps in better understanding regarding the subshells and how the electrons are filled inside these subshells.