But like other principles, there are also some limitations to this. The exchange interaction creates a state of electron configuration with the non-bonded electrons, all of them being of an interchangeable quantum state.Īufbau's principle says that electrons fill atomic orbitals of the lowest available energy state before occupying the upper level. It is also called exchange energy or exchange force. The exchange interaction may be an aggregate mechanical effect that occurs between the indistinguishable particles. So, this rule by Hund is useful to predict the ground state of atoms only in the case, when there is an availability of equal energy orbitals.

In other words, the rule says that the lowest-energy electronic configuration is attained with the utmost number of parallel electron spins. The electrons will have the same spin to increase the multiplicity in the orbitals. As per this principle, electrons pairing up in p, d, and f orbitals can’t occur until there is one electron each in the orbit of a given subshell.Įlectrons will first fill the orbitals singly if two or more orbitals are available and then fill doubly.

Obeys Hund's Rule of Maximum Multiplicity:Īccording to Hund’s rule of maximum multiplicity, in a given electron arrangement, the maximal multiplicity falls lowest in energy.

There are 4 quantum numbers principles (n), azimuthal (l), magnetic (m), and spin(s). Each electron in an atom must have a special set of quantum numbers. This Pauli Exclusion Principle states that one orbital can contain only two electrons with opposite spin which means any atomic orbital cannot accommodate more than two electrons with opposite spin.

Aufbau principle order