Key Notes On Hund’s Rule

In accordance with Hund’s rule, Every orbital in the sub level is singly occupied prior to the double occupancy of any orbital in the sub level. In order to maximise total spin, all electrons in a single occupancy orbital must have the same spin as one another.

An electron will not pair with another electron in a half-filled orbital because it has the capacity to fill all of its orbitals with energy that is comparable to that of the other electron. In atoms in their ground state, there are a large number of unpaired electrons present. When two electrons come into touch, they exhibit the same behaviour as when two magnets come into contact. Before they have to pair up, the electrons initially strive to go as far apart from one another as they possibly can before they have to couple up.

Maximum Multiplicity according to Hunds’ Rule of Maximum Multiplicity

Specifically, the Hund’s Rule of Maximum Multiplicity rule asserts that for a given electron configuration, the term with the greatest multiplicity has the least amount of energy. As a result of this rule, electron pairing in the lower energy levels of the p, d, and f orbitals is not possible until each orbital of a particular subshell has one electron or is single-occupied.

Hund’s Rule should be followed.

It says the following:

1. Prior to being doubly occupied in a sublevel, each orbital in the sublevel is singly occupied.
2. The electrons present in singly occupied orbitals all have the same spin as one another.

Hund’s Rule 

In order to couple up, the electrons must first enter an empty orbital. Because they are negatively charged, electrons are attracted to one another. Because the electrons do not share orbitals, the repulsion between them is reduced.

When we examine the second rule, the spins of unpaired electrons in singly occupied orbitals are the same as those of paired electrons in unoccupied orbitals. The spin of the first electrons in the sub-level determines the spin of the subsequent electrons in the sub-level. For example, the electron configuration of a carbon atom would be 1s22s22p2 in this case. As a result of Hund’s rule, the two 2s electrons will occupy the same orbital, despite the fact that the two 2p electrons will occupy two separate orbitals.

The Configuration of Electrons and the Functions of Electrons

Electron Configuration is a technical term that refers to the configuration of electrons in a molecule.

Understanding the electrical arrangement and its function is made easier with the aid of the illustration above. After coming into touch with each other, the initial interaction will occur between the valence shells of two atoms. When the valence shells of an atom are not completely filled, the atom is the least stable. The valence electrons of an element have a significant role in the chemical properties of the element. Chemical features that are similar in nature may be seen in elements with comparable valence values.

The electron configuration may also be used to forecast the stability of a system. When an atom’s orbitals are completely filled, it is at its most stable. Noble gases, for example, are the most stable orbitals because they contain a complete energy level in their orbitals. There is no reaction between these types of elements and other elements.

Hund’s rule of maximum multiplicity is a mathematical formula that describes the greatest number of possibilities in a given situation. The rule asserts that, for a given electron configuration, the spin multiplicity with the largest value has the lowest energy term, and vice versa. It states that if two or more than two orbitals with the same amount of energy are left vacant, the electrons will begin to occupy them individually before filling them in pairs with the energy they possess. An observation of an atomic spectrum is required in order to apply this rule, which may be useful in forecasting the ground state of a molecule or an atom that has one or more open electronic shells

Conclusion 

Therefore it can be concluded, Hund’s Rule is useful in a variety of situations, including the following: It is primarily used in atomic chemistry, quantum chemistry, and spectroscopy, among other fields of study. Friedrich Hund developed this rule in 1925, and it has been in use ever since.