Electron Configuration Chart

The Electron Configuration Chart is a science reference tool covering electron configuration chart, electron configuration table, electron configuration periodic table, noble gas configuration chart. Use the chart below to look up values instantly. Printable and downloadable versions are available on this page.

Electron Configuration Lookup

Enter an element name, symbol, or atomic number to get its full configuration, noble gas shorthand, and orbital diagram.

Covers H–Kr (Z 1–36) plus selected elements. For all elements see the NIST Periodic Table.
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Electron Configuration Chart — All Elements

Electron configuration describes the arrangement of electrons in an atom's orbitals — written in the format where each subshell label shows the principal quantum number, orbital type, and number of electrons as a superscript.

Electron Configurations of All Elements — Z 1 to 36
Element Symbol and Atomic Number Full Electron Configuration Noble Gas Shorthand Configuration
H — Hydrogen, Z=11s¹1s¹
He — Helium, Z=21s²1s²
Li — Lithium, Z=31s² 2s¹[He] 2s¹
Be — Beryllium, Z=41s² 2s²[He] 2s²
B — Boron, Z=51s² 2s² 2p¹[He] 2s² 2p¹
C — Carbon, Z=61s² 2s² 2p²[He] 2s² 2p²
N — Nitrogen, Z=71s² 2s² 2p³[He] 2s² 2p³
O — Oxygen, Z=81s² 2s² 2p⁴[He] 2s² 2p⁴
F — Fluorine, Z=91s² 2s² 2p⁵[He] 2s² 2p⁵
Ne — Neon, Z=101s² 2s² 2p⁶[He] 2s² 2p⁶
Na — Sodium, Z=111s² 2s² 2p⁶ 3s¹[Ne] 3s¹
Mg — Magnesium, Z=121s² 2s² 2p⁶ 3s²[Ne] 3s²
Al — Aluminium, Z=131s² 2s² 2p⁶ 3s² 3p¹[Ne] 3s² 3p¹
Si — Silicon, Z=141s² 2s² 2p⁶ 3s² 3p²[Ne] 3s² 3p²
P — Phosphorus, Z=151s² 2s² 2p⁶ 3s² 3p³[Ne] 3s² 3p³
S — Sulfur, Z=161s² 2s² 2p⁶ 3s² 3p⁴[Ne] 3s² 3p⁴
Cl — Chlorine, Z=171s² 2s² 2p⁶ 3s² 3p⁵[Ne] 3s² 3p⁵
Ar — Argon, Z=181s² 2s² 2p⁶ 3s² 3p⁶[Ne] 3s² 3p⁶
K — Potassium, Z=191s² 2s² 2p⁶ 3s² 3p⁶ 4s¹[Ar] 4s¹
Ca — Calcium, Z=201s² 2s² 2p⁶ 3s² 3p⁶ 4s²[Ar] 4s²
Sc — Scandium, Z=211s² 2s² 2p⁶ 3s² 3p⁶ 3d¹ 4s²[Ar] 3d¹ 4s²
Ti — Titanium, Z=221s² 2s² 2p⁶ 3s² 3p⁶ 3d² 4s²[Ar] 3d² 4s²
V — Vanadium, Z=231s² 2s² 2p⁶ 3s² 3p⁶ 3d³ 4s²[Ar] 3d³ 4s²
Cr — Chromium, Z=24 Exception[Ar] 3d⁵ 4s¹[Ar] 3d⁵ 4s¹
Mn — Manganese, Z=251s² 2s² 2p⁶ 3s² 3p⁶ 3d⁵ 4s²[Ar] 3d⁵ 4s²
Fe — Iron, Z=261s² 2s² 2p⁶ 3s² 3p⁶ 3d⁶ 4s²[Ar] 3d⁶ 4s²
Co — Cobalt, Z=271s² 2s² 2p⁶ 3s² 3p⁶ 3d⁷ 4s²[Ar] 3d⁷ 4s²
Ni — Nickel, Z=281s² 2s² 2p⁶ 3s² 3p⁶ 3d⁸ 4s²[Ar] 3d⁸ 4s²
Cu — Copper, Z=29 Exception[Ar] 3d¹⁰ 4s¹[Ar] 3d¹⁰ 4s¹
Zn — Zinc, Z=301s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s²[Ar] 3d¹⁰ 4s²
Ga — Gallium, Z=311s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p¹[Ar] 3d¹⁰ 4s² 4p¹
Ge — Germanium, Z=321s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p²[Ar] 3d¹⁰ 4s² 4p²
As — Arsenic, Z=331s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p³[Ar] 3d¹⁰ 4s² 4p³
Se — Selenium, Z=341s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁴[Ar] 3d¹⁰ 4s² 4p⁴
Br — Bromine, Z=351s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁵[Ar] 3d¹⁰ 4s² 4p⁵
Kr — Krypton, Z=361s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶[Ar] 3d¹⁰ 4s² 4p⁶

Chromium (Z=24) and Copper (Z=29) are the two most commonly tested exceptions to the Aufbau filling order. Both adopt configurations that give a half-filled or fully filled 3d subshell rather than filling the 4s first — these configurations are energetically more stable.

Source: NIST Chemistry WebBook and standard general chemistry references — LibreTexts Chemistry — Electronic Configurations

Subshell Filling Order — Aufbau Principle

The Aufbau principle states that electrons fill subshells in order of increasing energy — the filling order can be remembered using the diagonal arrow diagram.

1s 2s 2p 3s 3p 4s 3d 4p 5s 4d 5p 6s 4f 5d 6p 7s 5f 6d 7p

Subshell capacities:

  • Each s subshell holds a maximum of 2 electrons
  • Each p subshell holds a maximum of 6 electrons
  • Each d subshell holds a maximum of 10 electrons
  • Each f subshell holds a maximum of 14 electrons
Remember SPDF capacities as 2, 6, 10, 14 — increasing by 4 each time. This follows from the number of orbitals in each subshell: s has 1 orbital, p has 3, d has 5, f has 7 — each orbital holds 2 electrons.

Orbital Notation Rules

  1. Aufbau Principle — electrons fill subshells starting from the lowest energy (1s) upward to higher energy levels before filling the next subshell.
  2. Pauli Exclusion Principle — no two electrons in the same atom can have identical quantum numbers. Each orbital holds a maximum of 2 electrons and they must have opposite spins (one up ↑ and one down ↓).
  3. Hund's Rule — when filling degenerate orbitals (equal energy orbitals within the same subshell), electrons occupy each orbital singly before any orbital is doubly occupied. All single electrons have parallel spins. Example: carbon has 2 unpaired electrons in separate 2p orbitals, not 1 doubly-occupied 2p orbital.
  4. Exceptions to Aufbau — Chromium (Cr) and Copper (Cu) are the most important exceptions. Both adopt configurations where a 3d subshell is half-filled (Cr) or fully filled (Cu) because these are unusually stable configurations. Cr is [Ar] 3d⁵ 4s¹ and Cu is [Ar] 3d¹⁰ 4s¹.

Electron Configuration Lookup

Enter an element name, symbol, or atomic number to get its full configuration, noble gas shorthand, orbital diagram, and any exception notes.

Covers H–Kr (Z 1–36) plus selected elements. For all elements see the NIST Periodic Table.

Frequently Asked Questions

What is electron configuration?

Electron configuration describes how electrons are distributed among the orbitals of an atom. It is written by listing each occupied subshell with its electron count as a superscript — for example carbon is 1s² 2s² 2p².

How do you write electron configuration?

Fill subshells in Aufbau order (1s, 2s, 2p, 3s, 3p, 4s, 3d...) adding electrons until you reach the atom's atomic number. For noble gas shorthand use the symbol of the preceding noble gas in brackets then continue from there.

What is the electron configuration of oxygen?

Oxygen (Z=8) is 1s² 2s² 2p⁴ or in shorthand [He] 2s² 2p⁴.

What is the electron configuration of iron?

Iron (Z=26) is [Ar] 3d⁶ 4s² in its neutral state. In the common Fe²⁺ ion it loses the 4s electrons first giving [Ar] 3d⁶.

Why is chromium's electron configuration an exception?

Chromium is [Ar] 3d⁵ 4s¹ instead of the expected [Ar] 3d⁴ 4s². A half-filled 3d subshell with one electron in 4s is more stable than a partially filled 3d⁴ — this extra stability makes the exception energetically favourable.

What is the noble gas shorthand configuration?

Noble gas shorthand replaces the inner core electron configuration with the symbol of the preceding noble gas in brackets. For sodium the full configuration is 1s² 2s² 2p⁶ 3s¹ which is written as [Ne] 3s¹ because neon (1s² 2s² 2p⁶) is the preceding noble gas.

How many electrons does a 3d subshell hold?

A 3d subshell holds a maximum of 10 electrons — it contains 5 orbitals and each orbital holds 2 electrons with opposite spins.

What is Hund's rule?

Hund's rule states that electrons occupy each degenerate orbital (equal-energy orbital within the same subshell) singly before any is doubly occupied. All singly-occupied orbitals have parallel spins — this minimises electron repulsion and results in a more stable lower-energy state.

Also check out:

Electronegativity Chart Molecular Geometry Chart Amino Acid Chart Codon Chart Solubility Chart