The electron configuration of the element is the basis of the periodic table. The group and period, block, valence, and valence electrons of an element are determined by electron configuration. This article will discuss the electron configuration in detail and the electron configuration of all the elements.

The nucleus is located in the center of the atom. And protons and neutrons are located in the nucleus. The number of protons in the nucleus of an atom is the atomic number. The electrons revolve around the atom. This number of electrons is equal to the number of protons and atoms. Electrons are arranged in the orbits of the atom at certain distances and certain rules around the atom.

The arrangement of electrons in different orbits and orbitals of an atom in a certain order is called electron configuration. The electron configuration of 118 elements of the periodic table can be done in 2 ways.

- Electron configuration via orbit.
- Electron configuration via orbital.

Electron configuration through orbitals follows different principles. For example, the Aufbau principle, Hund’s principle, Pauli’s exclusion principle.

Table of Contents

## Definition of Orbit

Scientist Niels Bohr was the first to give an idea of the orbit of the atom. In 1913, scientist Bohr proposed a policy regarding the orbit of the atom. There, he said, the electrons of the atom continue to rotate in a certain circular path. The electrons of an atom revolve in circular paths at certain rules and distances, these circular paths are called orbits. And, the method of arranging electrons in these circular orbits is called the method of electron configuration through orbits. Orbits are expressed by n. [n = 1,2,3,4 …]

K is the name of the first orbit, L is the second, M is the third, N is the name of the fourth orbit. The electron holding capacity of each orbit is 2n^{2}. [ n = 1,2 3,4 …..].

Now,

n = 1 for K orbit.

The electron holding capacity of K orbit is 2n^{2} = 2 × 1^{2} = 2 electrons.

For L orbit, n = 2.

The electron holding capacity of the L orbit is 2n^{2} = 2 × 2^{2} = 8 electrons.

n=3 for M orbit.

The maximum electron holding capacity in M orbit is 2n^{2} = 2 × 3^{2 }= 18 electrons.

n=4 for N orbit.

The maximum electron holding capacity in N orbit is 2n^{2} = 2 × 3^{2} = 32 electrons.

The electron holding capacity of each orbit of the element is 2n^{2}. The serial number of the orbit. [n = 1,2,3,4 . . . ]

Therefore, the maximum electron holding capacity in the first orbit is 2. The maximum electron holding capacity in the second orbit 8. the 3rd orbit can have a maximum of 18 electrons. And the 4th orbit can have a maximum of 32 electrons.

## Definition of Orbital

Atomic energy levels are subdivided into sub-energy levels. These sub-energy levels are called orbital. The sub energy levels are expressed by ‘l’. The value of ‘l’ is from 0 to (n – 1). The sub-energy levels are known as s, p, d, f.

Determining the value of ‘l’ for different energy levels is-

If n = 1,

(n – 1) = (1–1) = 0

Therefore, the orbital number of ‘l’ is 1; And the orbital is 1s.

If n = 2,

(n – 1) = (2–1) = 1.

Therefore, the orbital number of ‘l’ is 2; And the orbital is 2s, 2p.

If n = 3,

(n – 1) = (3–1) = 2.

Therefore, the orbital number of ‘l’ is 3; And the orbital is 3s, 3p, 3d.

If n = 4,

(n – 1) = (4–1) = 3

Therefore, the orbital number of ‘l’ is 4; And the orbital is 4s, 4p, 4d, 4f.

If n = 5,

(n – 1) = (n – 5) = 4.

Therefore, l = 0,1,2,3,4. The number of orbitals will be 5 but 4s, 4p, 4d, 4f in these four orbitals it is possible to arrange the electrons of all the elements of the periodic table. Electron configuration through orbital follows different principles. For example, the Aufbau principle, Hund’s principle, Pauli’s exclusion principle.

## Electron Configuration in the Aufbau principle

The German physicist Aufbau first proposed the idea of electron configuration through sub-orbits. The Aufbau method is to do electron configuration through the sub-energy level. These sub-orbitals are expressed by ‘l’. The Aufbau principle is that the electrons present in the atom will first complete the lowest energy orbital and then gradually continue to complete the higher energy orbital.

These orbitals are named s, p, d, f. The electron holding capacity of these orbitals is s = 2, p = 6, d = 10 and f = 14. The Aufbau electron configuration method is 1 s 2s 2p 3s 3p 4s 3d 4p 5s 4d 5p 6s 4f 5d 6p 7s 5f 6d.

## Electron configuration in the Hund’s principle

The German physicist Friedrich Hund provided a guideline for the entry of electrons into different orbitals of equal power. Which is known as Hund’s principle. Hund’s principle is that when electrons enter the orbitals of equal power, the electrons will randomly enter the orbital as long as the orbital is empty. And the spin of these unpaired electrons will be one-sided.

But does not support Hund’s principle in s-orbital. This is because the s-orbital has only one orbital and the s-orbital cannot be divided. Therefore, Hund’s principle does not apply when electrons enter the s-orbital.