Helium orbital diagram

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Helium orbital diagram
Helium orbital diagram | Image: Learnool

In the helium orbital diagram, the 1s subshell accommodates two electrons.

To illustrate the helium orbital diagram, first, determine the number of electrons from the periodic table. Then, note the electron configuration for reference, and follow the three essential rules: Aufbau principle, Pauli exclusion principle, and Hund’s rule. This systematic approach ensures an accurate representation of helium’s orbital arrangement.


Find electrons

A periodic table showcasing 118 elements, listed in increasing order of atomic numbers | Image: Learnool

To find the number of electrons in a helium atom, check its atomic number on the periodic table. Helium’s atomic number is 2, indicating it has two electrons.

Write electron configuration

The electron configuration of helium is 1s2.

Now in the next step, start drawing the orbital diagram for helium.

Draw orbital diagram

Before drawing the orbital diagram, you should know the three general rules.

  • Aufbau principle – electrons are first filled in lowest energy orbital and then in higher energy orbital
  • Pauli exclusion principle – two electrons with the same spin can not occupy the same orbital
  • Hund’s rule – each orbital should be first filled with one electron before being paired with a second electron

Also, you should know the number of orbitals in each subshell.

We can calculate the number of orbitals in each subshell using the formula: 2ℓ + 1

Where, ℓ = azimuthal quantum number of the subshell

For s subshell, ℓ = 0
For p subshell, ℓ = 1
For d subshell, ℓ = 2
For f subshell, ℓ = 3

So each s subshell has one orbital, each p subshell has three orbitals, each d subshell has five orbitals, and each f subshell has seven orbitals.

Now start to draw!

As mentioned above, the electron configuration of helium is 1s2. Hence, draw the blank orbital diagram of helium up to 1s subshell as follows:

Blank orbital diagram of helium | Image: Learnool

In the above orbital diagram, the box represents an orbital. Each orbital has a capacity of two electrons. And the arrows (↑↓) are drawn inside the box to represent electrons.

Now 1s2 indicates that the 1s subshell has 2 electrons. So draw two arrows in the 1s box showing two electrons as follows:

Two arrows drawn in 1s box represent 1s2 | Image: Learnool

That’s it! This is the final orbital diagram of helium as we have used all 2 electrons.

Next: Lithium orbital diagram


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