orbital filling diagram calculator

How to Calculate Orbital Diagrams?

The orbital diagram simply represents the arrangement of electrons in the different orbitals of an atom, it uses an arrow to represent the electrons, every orbital(one box) contains a maximum of 2 electrons.

There are three rules followed for calculating the orbital diagram for an atom.

(1). Aufbau’s principle:- This rule states that the lower energy orbital will be filled before the higher energy orbital, for example – the 1s orbital will fill before the 2s orbital.

(2). Hund’s rule:- This rule states that each orbital of a given subshell should be filled with one electron each before pairing them. That means “Each orbital gets one electron first, before adding the second electron to the orbital”.

(3). Pauli Exclusion Principle:- This rule states that, no two electrons can occupy the same orbital with the same spin. That means “One must be spin up (↑) and one must be spin down (↓)”.

If you understand the above rules then calculating the orbital diagram or orbital notation for any atom is super easy.

Basics of Orbital diagram:-

There are different types of orbitals – s, p, d, and, f. These orbitals contain a number of boxes that can hold a number of electrons. Let’s see.

Each box will hold a maximum of 2 electrons with opposite spin.

• S orbital contains 1 box that can hold a maximum of 2 electrons.
• P orbital contains 3 boxes that can hold a maximum of 6 electrons.
• D orbital contains 5 boxes that can hold a maximum of 10 electrons.
• F orbital contains 7 boxes that can hold a maximum of 14 electrons.

The orbital diagram will be filled in the same order as described by the Aufbau principle.

“The Aufbau principle states that electrons will inhabit the lowest-energy orbitals first. This means that electrons can only enter higher-energy orbitals after lower-energy orbitals have been entirely filled.”

We have a diagonal rule for electron filling order in the different subshells using the Aufbau principle.

So, the order in which the orbitals are filled with electrons from lower energy to higher energy is –

 1s < 2s < 2p < 3s < 3p < 4s < 3d < 4p < 5s < 4d < 5p < 6s < 4f < 5d < 6p < 7s < 5f < 6d < 7p and so on.

Trick:- you can learn the order of the orbital box diagram and then fill out the electrons in it.

How to calculate an Orbital diagram/notation for any atom?

To calculate the orbital diagram for an atom, follow these basic steps-

1. Find the number of electrons in an atom.
2. Write the electron configuration for an atom to determine which orbitals should be filled.
3. Fill the electrons in empty boxes using three principles – Aufbau, Hund’s, and Pauli Exclusion.

Let’s take an example of the Nitrogen atom to understand the concept of the making of filling the orbital diagram.

How to calculate an Orbital diagram for Nitrogen?

We know that the nitrogen atom has a total of 7 electrons that need to be placed into orbitals, now for calculating its orbital diagram, we need to show its electrons in form of an arrow in different boxes using Aufbau, Hund’s, and Pauli’s exclusion rule.

• Nitrogen has a total of 7 electrons and its electron configuration is 1s²2s²2p³.
• As per the Aufbau rule, the electrons will be filled into 1s orbital first then 2s, then 2p…so on.
• 1s orbital contains 1 box, 2s orbital also contains 1 box and 2p orbital contains 3 boxes. Also, one box can hold up to two electrons.
• Therefore, the first two electrons of nitrogen will go in the 1s orbital, and the next two will go in the 2s orbital, now we are left with 3 electrons.
• These 3 electrons will go in the 2p orbital, since, the 2p orbital has 3 boxes, so, these electrons will be filled using Hund’s rule. (Each box gets one electron first).

Let’s take one more example to understand the procedure of calculating the orbital diagram for an atom.

How to calculate an Orbital diagram for Potassium?

We know the potassium has a total of 19 electrons that need to be placed into orbitals, now for calculating its orbital diagram, we need to show its electrons in form of an arrow in different boxes using Aufbau, Hund’s, and Pauli’s exclusion rule.

• Potassium has a total of 19 electrons and its electron configuration is 1s²2s²2p⁶3s²3p⁶4s¹.
• As per the Aufbau rule, the electrons will be filled into 1s orbital first then 2s, then 2p…so on.
• 1s orbital contains 1 box, 2s orbital also contains 1 box, 2p orbital contains 3 boxes, 3s orbital contains 1 box, 3p orbital contains 3 boxes, and 4s orbital contains 1 box.  Also, one box can hold up to two electrons.
• Therefore, the first two electrons of potassium will go into the 1s orbital, the next two will go into the 2s orbital, and after that, the next six electrons will go into the 2p orbital, since, the 2p orbital has 3 boxes.
• After that, the next two electrons will go in the 3s orbital, and the next six electrons will enter the 3p orbital. Now, the 3p orbital is full.
• Therefore, the remaining one electron will go in 4s orbital in the clockwise direction. (↑)