Aufbau Principle Definition

Aufbau’s Principle states that

“Electrons in different orbitals are filled in the increasing order of their energy, i.e. the orbital with the lowest energy will be filled first and the orbital with the highest energy will be filled last.”

The word ‘Aufbau’ in German means ‘Building up’. Formation of orbitals means filling orbitals with electrons. It states that the electrons in atomic orbitals are filled in the ascending order of the energy of the atomic orbital. And the energy of the atomic orbital is calculated using the “n+l” rule that states if the electron with a higher number of the n+l value has the higher energy. In the rule discussed in the previous line, n tells the Principal Quantum number and l tells the Azimuthal Quantum number.

If two electrons have the same value of “n+l” then the electron with a smaller value of n has the smaller energy and is filled first. The order of filling the electrons in an atomic orbital is discussed below.

Aufbau Principle Diagram

The Aufbau Principle Diagram is the diagram that depicts the order of filling the electrons in an atom.

Aufbau Principle Formula

The Aufbau Principle Formula is the formula that tells the order in which the electrons are filled in the atomic orbital. The atomic orbital formula is

1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p, 5s, 4d, 5p, 6s, 4f, 5d, 6p, 7s, 5f, 6d, 7p…….

Aufbau Principle Class 11

Aufbau Principle is an important principle of Chemistry for the students in class 11. This principle states that,

“The electrons in the atomic orbital of an atom is filled in the ascending order of the energy of the atomic orbital that is calculated using (n+l) rule.”

Aufbau Principle is the basic method that tells us how the electrons are filled in the atomic orbital. According to the Aufbau Principle, the filling of the electrons in the ground state of an atom follow a basic pattern. This principle tells us that the electrons in the atomic orbital of any atoms are filled in the ascending order of their energy and for finding the energy of the atomic orbital they follow the “n+l” rule.

In this article, we will learn about Aufbau Principle, Features of the Aufbau Principle, its exceptions and limitations in detail.