Electron Configuration Calculator

Enter an atomic number or choose an element to find its ground-state electron configuration, noble gas notation, shell distribution, valence electrons, period, and block.

Elements 1–118 Shell Distribution Noble Gas Notation

Calculate Electron Configuration

Choose an element or enter its atomic number.

Neutral atoms: For a neutral atom, the number of electrons equals its atomic number. This calculator returns the ground-state configuration and includes commonly recognized configuration exceptions.

Atomic Number

Atomic Number (Z) Enter a whole number from 1 to 118.

Select Element

Element Selecting an element automatically updates its atomic number.

Orbital Filling Order
1s → 2s → 2p → 3s → 3p → 4s → 3d → 4p → 5s → 4d → 5p → 6s → 4f → 5d → 6p → 7s → 5f → 6d → 7p

Iron

Atomic Number 26

Full Electron Configuration

Noble Gas Notation

Total Electrons -

Valence Electrons -

Period -

Block -

Electrons Per Shell

Chemistry Guide

What Is Electron Configuration?

Electron configuration describes how electrons are distributed among the orbitals of an atom. Orbital labels such as 1s, 2s, 2p, and 3d identify the principal energy level and subshell occupied by electrons.

For a neutral atom, the total number of electrons in the configuration equals the atomic number of the element. Electron configurations are useful for understanding periodic trends, chemical behavior, and valence electrons.

Filling Order

Electron Configuration Filling Order

Orbitals are filled according to increasing orbital energy. Each type of subshell also has a maximum electron capacity.

1s → 2s → 2p → 3s → 3p → 4s → 3d → 4p The sequence continues through the higher-energy orbitals required for heavier elements.

Subshell	Number of Orbitals	Maximum Electrons
s	1	2
p	3	6
d	5	10
f	7	14

How It Works

How to Use the Electron Configuration Calculator

Choose an Element

Select an element from the list or enter its atomic number from 1 to 118.

Calculate Configuration

The tool determines the ground-state orbital occupancy for the selected neutral atom.

Review the Results

See the full configuration, noble-gas shorthand, shell distribution, valence electrons, period, and block.

Worked Example

Electron Configuration Example

Example: Iron (Fe)

Iron has atomic number 26, so a neutral iron atom contains 26 electrons.

Its full ground-state electron configuration is:

1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d⁶

Noble gas shorthand: [Ar] 4s² 3d⁶

Notation Guide

How to Read Electron Configuration

Part	Meaning	Example
Number	Principal energy level	3 in 3p⁶
Letter	Subshell type	p in 3p⁶
Superscript	Number of electrons in that subshell	6 in 3p⁶
[Noble Gas]	Inner-electron shorthand	[Ar]

Note: Some elements have ground-state configurations that differ from the simplest Aufbau prediction. The calculator includes a reference set of commonly accepted ground-state configurations rather than relying only on a basic filling algorithm.

Frequently Asked Questions

Electron Configuration Calculator FAQs

What is electron configuration?

Electron configuration is a notation describing how an atom's electrons occupy its energy levels, subshells, and orbitals.

How many electrons does a neutral atom have?

A neutral atom has the same number of electrons as its atomic number because its number of electrons equals its number of protons.

What is noble gas notation?

Noble gas notation replaces the completed inner electron configuration with the symbol of the preceding noble gas in square brackets.

What is the maximum capacity of an s subshell?

An s subshell contains one orbital and can hold a maximum of two electrons.

How many electrons can a p subshell hold?

A p subshell contains three orbitals and can hold up to six electrons.

How many electrons can d and f subshells hold?

A d subshell can hold up to 10 electrons, while an f subshell can hold up to 14 electrons.

Does the calculator support all 118 elements?

Yes. You can select an element or enter an atomic number from 1 through 118.

Does this calculator calculate ions?

This version is designed for neutral atoms. The displayed electron count therefore matches the selected element's atomic number.