Helium Electron Configuration: 7 Facts You Should Know!

Electronic configuration describes the distribution of electrons in an element’s atomic orbitals. Let us discuss more about the He and its electronic configuration in detail.

1s2 is the electronic configuration of Helium (He) with atomic number 2. It is located in the s block of the periodic table and belongs period one and group 18. Since the atomic orbital of the atoms is already complete, this element is classified as a noble gas.

The electronic configuration, notation, and diagram of He, in addition to the specifics of the information regarding it will be discussed in this article.

How to write Helium electron configuration

The electronic configuration of He is 1s2 which is written using the following steps.

  • Determine the element’s energy level, which corresponds to its period. Here, He belongs to the first period and consists of just two electrons.
  • The next step is to determine the number of electrons that corresponds to the atomic number. Which is 2, and both the electron will be accommodated in 1s subshell level as it can hold 2 electrons.
  • Then electron will be filled according to the sequence model, according to 1s 2s 2p, and so on, so in the case of He, as it has only 2 electrons, so its configuration is 1s2.

Helium electron configuration diagram

Using the octet rule, the electron configuration of the helium 1s2 is drawn in the given image below.

Helium electronic configuration diagram

Helium electron configuration notation

The electronic configuration notation of He is [He] 1s2

Helium unabbreviated electron configuration

The unabbreviated electronic configuration of He is 1s2. As it contains only 2 electrons so its unabbreviated electron configuration is the same as the electronic configuration.

Ground state Helium electron configuration

The ground state electronic configuration of He is 1s2.

Excited state of Helium electron configuration

[He]=1s1 2s1 is the initial excited state electronic configuration of Helium, which is characterized by the shifting of one electron from a 1s orbital to a 2s orbital.

Ground state helium orbital diagram

The atomic orbital diagram for the He in the ground state is shown below.

Molecular orbital diagram of He in the ground state


The article has discussed the electrical configuration of helium, which is 1s2 and consists of the noble gas’s configuration through the use of this article. Whereas we have also discussed the ground, excited state, and molecular orbital diagram. Where the excited state configuration has changed to 1s1 and 2s1.

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