Hunds Rule | Hund’s Rule of Maximum Multiplicity & Explaination 1st year Book
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Hunds Rule of Maximum Multiplicity

On the basis of magnetic measurements, Hund postulated an important empirical rule popularly known after his name as Hund’s Rule. This rule has a spectroscopic basis and is applied when orbitals of a sub-group of an atom are incompletely occupied. This rule may be defined as :

                    Electrons prefer to occupy separate orbitals so that they have parallel spins:

or’ When electrons are added in a set of orbitals in a given subshell (p- d- or f-) never pair up until all the available orbitals do not have one electron each.
(As students in a classroom prefer to occupy a single separate seat until all the chairs do not fill). Thus, it is a natural law.

Both the above statements have the same meaning that the pairing of electrons will occur in a set of orbitals of equivalent energies only when all the available orbitals do not contain one electron each. The atoms, ions, or molecules obeying the above statements are known to be thermodynamically more stable.

Hunds Rule Explanation :

To explain Hund’s rule, let us consider there are three electrons that are allowed to enter p-orbitals, their distribution will be:

Hunds rule, hund's law, state hund's rule of maximum multiplicity

Thus, it is clear from the above configurations that pairing begins with the introduction of the 2nd electron in the s-orbital, the 4th electron in p-orbitals, the 6th in d-orbitals, and the 8th electron in f-orbitals. These can be shown by the following representations.

Hunds rule, Hunds rule electronic configration

Hund’s rule also states that an atom containing empty  (p°, d°, or f°), completely half-filled, or completely full-filled (p3, d5, or f7) orbitals will have more stability as compared to other arrangements. Because such arrangements provide symmetry. In other words, empty, completely half-filled, and completely full-filled orbital provide extra stability to an atom or other species.

Related Topic | Atomic Structure and Periodic Table

Bohr’s Atomic ModelDe Broglie Hypothesis
De Broglie EquationHeisenberg uncertainty Principle
Schrodinger Wave EquationShapes of orbitals
Quantum NumbersHunds Rule
Pauli Exclusion PrincipleEnergy level diagram of Atom
Aufbau PrincipleScreening effect or shielding effect
Periodic TableMoseley Periodic law
Classification of elements 

Hunds Rule Importance :

(i) Hund’s rule plays an important role in interpreting the diamagnetic and paramagnetic properties of various ions, molecules, and complex compounds. For example, a Cupprus ion Cu++ consisting of no unpaired electron is diamagnetic whereas a cuprous ion Cu++ is paramagnetic due to the presence of one unpaired d-electron as clear from the following electronic configurations:

(ii) This rule satisfactorily explains how an atom exhibits more than one electro-valency for metals and co-valency for non-metals. For example :

Hund's rule, hunds rule electronic configuration of diamagnetic, hunds rule electronic configuration of diamagnetic

(a) Copper exhibits +1 electro-valency when it follows Hund’s rule and +2 when it does not follow Hund’s rule.
(b) Phosphorus has minimum covalency of 3 in-ground states and a maximum covalency of 5 in an excited state.

hunds rule energy distribution, hunds rule, hunds rule of energy distribution of neon ne
(iii) This rule explains the relative stability of the Oxyacids of transition metals.
(iv) Hund’s rule also explains the possible number of states or levels of various species.

Frequently Asked Questions

The Hunds rule develop. When scientists hunds working on electron distribution in orbitals. He finds that each orbital has a different energy level occupied by different no. of electrons on the different shells. Where he observed that each subgroup of orbital 1st occupied a single electron on every subgroup of the orbital. Then it’s occupying double.


Hund’s rule: Each subshell of orbitals is first singly occupied or filled. Then, it’s going to occupy another half of the subshell. This means that the first half subshell will be filled and then doubled.

State of Hund’s Rule :

1. The orbital of the subgroup is occupied signal 1st in every subshell or subgroup. Then it goes doubly occupied.

2. The orbital of a subshell or subgroup which is singly occupied or half filled have their identical skin.

Example 1: Fluorine (F)

We can consider the correct electron configuration of the fluorine (Z=9) Atom: 1s2 2s2 2p5

1s22s2 2p5 



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