Examples of Electron configuration

In this section we present some examples of Electron configuration, necessary to understand a little more the elements of the periodic table.

There are four ways to graphically represent the Electron configuration of a chemical element, where the number of electrons that the atom has must always be taken into account, which corresponds to the atomic number of said element.

Example of standard Electron configuration

Here, the square of the diagonals is used, where the orbitals are filled with the electrons of the atom as they appear, taking into account that these start with 1s.

For any atom, the standard configuration is:

1s2 2s2 2s6 3s2 3s6 4s2 3d10 4s6 5s2 4d10 5s6 6s2 4f14 5d10 6s6 7s2 5f14 6d10 7s6

Example:

Lithium has 3 electrons which correspond to its same atomic number, i.e. z=3.

These three electrons are split between the 1s orbital, which fills with two of these electrons, and the 2s orbital, which fills with the missing electron for a total of 3 electrons.

Thus obtaining the following configuration: 1s22s1

Example of condensed electron configuration

>It’s a way to perfectly simplify the standard configuration, which is usually a very long Electron notation.

In this case, it is represented by a rare gas, which is an element of group VIII A (He, Ar, Ne, Rn, Xe).

Here the atomic number of the gas close to the element to be configured coincides with the electrons which will fill the first orbitals of this element.

Example:

Following the same element of Lithium, the rare gas next to it will be taken to further simplify the standard configuration, in this case it corresponds to Helium, with the atomic symbol He.

As this one presents the same orbits that lithium has at its beginning, the atomic symbol of helium will be taken between parentheses then the missing orbit of lithium which does not have helium will be written, in this case 2s1 , thus obtaining the following simplified form: [He] 2s1

Expanded configuration

• Here you can represent each of the electrons that make up an atom using arrows that symbolize each of its spins.
• Here, Pauli’s exclusion principle is taken into account as well as Hund’s maximal rule on multiplicity to execute the conduct.

Semi-expanded configuration

It is a mix between the expanded configuration and the condensed configuration. Here, only the electrons of the last energy level are represented.

Video with examples of Electron configurations