Learning Objective: To study how the atomic orbitals of an atom are filled, and how the electronic configuration of an atom is written.
Skill Level – Intermediate
Prerequisites:
Orbitals (s, p, d, f)
Degenerate Orbitals
Empty atomic orbitals
Filled atomic orbitals
Electronic configuration
Inner versus outer nuclear part of an atom
Related –
Aufbau’s Principle
Hund's Rule
Quantum numbers (principal, angular, magnetic, spin)
Difference between Aufbau, Hund, and Pauli
Difference between shell and subshell
Tutorial on writing electronic configuration
Chapter: Atom
Author's Note: In the previous section, we studied how the electrons are housed in various orbitals and their representations.
In this section, we will explore how these atomic orbitals are occupied by the electrons and in what order, as stated by the Aufbau principle. We will also learn about scenarios where similar energies of atomic orbitals exist and then apply Hund's rule to fill them. The electronic configurations of simple p-block elements are shown as examples.
Filling of atomic orbitals and writing electronic configuration
The electron always occupies the lowest energy orbital first. The lowest energy orbitals are the ones that are closest to the nucleus. Therefore, the energy of the s orbital will be lower than p orbital, followed by the d and f orbitals.
Relative energies of the atomic orbitals:
1s < 2s < 2p < 3s < 3p < 3d
The filling of the atomic orbital by the lowest energy rule was proposed by Aufbau, known as Aufbau’s principle. Simply stated, the Aufbau's principle determines the order in which orbitals are filled across the entire electron configuration.
If an atom has two or more orbitals with the same energy (or degenerate, as seen in the 2p subshell as 2px, 2py, 2pz), in that case,....
For example, the carbon atom has six electrons in its outer nuclear region. ....
All the three p-orbitals of the 2nd level have identical shapes and energies in the carbon atom. Only their spatial orientation along the x, y, or z-axes varies......
Writing Electronic Configuration
The electronic configuration of some of the elements from the first and second rows of the periodic table are-...
As you can see from the above table, once the degenerate orbitals of .....
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