What is the electron configuration of aluminium?

Aluminium (Al, Z=13) has the ground-state electron configuration 1s² 2s² 2p⁶ 3s² 3p¹. The 13 electrons fill five subshells across three principal shells.

What is the noble-gas shorthand for aluminium?

The condensed (noble-gas) notation is [Ne] 3s² 3p¹, where [Ne] represents the filled 1s² 2s² 2p⁶ core shared with neon.

Why does aluminium form a +3 ion?

Aluminium loses its three valence electrons — two from 3s and one from 3p — to achieve the stable [Ne] (1s² 2s² 2p⁶) noble-gas core, resulting in the Al³⁺ ion.

How many valence electrons does aluminium have?

Aluminium has 3 valence electrons: 2 in the 3s subshell and 1 in the 3p subshell.

What block and period is aluminium in?

Aluminium is in Period 3, Group 13 (IIIA), and belongs to the p-block of the periodic table.

What is the difference in spelling — aluminium vs aluminum?

Both spellings refer to the same element (Z=13). "Aluminium" is the IUPAC-recommended spelling used internationally; "aluminum" is the spelling adopted by the American Chemical Society (ACS) and common in North America.

What is the orbital notation for the 3p electron in aluminium?

The single 3p electron occupies one of the three 2pₓ, 2p_y, or 2p_z orbitals with a spin of +½ (by convention, placed in the first available orbital with spin up).

Aluminium Electron Configuration

Name: Aluminium Electron Configuration
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Author: Nham Vu

Interactive reference for aluminium's electron configuration (1s² 2s² 2p⁶ 3s² 3p¹), orbital diagram, quantum numbers, and key atomic properties.

Z = 13 Al Aluminium

Aluminium — Electron Configuration

Atomic number 13 · Post-transition metal · Period 3, Group 13 · p-block

1s² 2s² 2p⁶ 3s² 3p¹ [Ne] 3s² 3p¹ 13 electrons 3 valence e⁻

Subshell Breakdown

Subshell	Type	Electrons	Max Capacity	Notation
1s	s orbital, shell n=1	2	2	1s²
2s	s orbital, shell n=2	2	2	2s²
2p	p orbitals, shell n=2	6	6	2p⁶
3s	s orbital, shell n=3	2	2	3s²
3p	p orbitals, shell n=3	1	6	3p¹
Total		13

Full Configuration

1s² 2s² 2p⁶ 3s² 3p¹

All subshells written explicitly.

Noble-Gas Shorthand

[Ne] 3s² 3p¹

[Ne] = 1s² 2s² 2p⁶ (the filled neon core).

Shell Fill Summary

Shell 1 (n=1) — 1s² 2 / 2 electrons (100%)

Shell 2 (n=2) — 2s² 2p⁶ 8 / 8 electrons (100%)

Shell 3 (n=3) — 3s² 3p¹ 3 / 18 electrons (17%)

Shell 3 can hold up to 18 electrons (3s + 3p + 3d). Aluminium uses only 3 of those 18 slots.

Orbital Box Diagram

2 electrons (paired) — filled

6 electrons across 3 orbitals — filled

2 electrons (paired) — filled

empty

1 electron (unpaired, spin up) — valence p electron

Each box represents one orbital. Opposing arrows represent paired electrons with opposite spins (+½ and −½). The single 3p electron follows Hund's rule — it occupies an empty orbital before pairing.

Quantum Numbers for All 13 Electrons

Electron #	n	l	mₗ	mₛ	Subshell
1	1	0	0	+½	1s
2	1	0	0	−½	1s
3	2	0	0	+½	2s
4	2	0	0	−½	2s
5	2	1	-1	+½	2p
6	2	1	-1	−½	2p
7	2	1	0	+½	2p
8	2	1	0	−½	2p
9	2	1	1	+½	2p
10	2	1	1	−½	2p
11	3	0	0	+½	3s
12	3	0	0	−½	3s
13	3	1	-1	+½	3p

n = principal quantum number; l = azimuthal (l=0 → s, l=1 → p); mₗ = magnetic; mₛ = spin.

Summary

Interactive reference for aluminium's electron configuration (1s² 2s² 2p⁶ 3s² 3p¹), orbital diagram, quantum numbers, and key atomic properties.

How it works

The Aufbau principle fills orbitals from lowest to highest energy.
Aluminium's 13 electrons occupy five subshells: 1s, 2s, 2p, 3s, and 3p.
The 2p subshell holds 6 electrons across three orbitals (2pₓ, 2p_y, 2p_z), each pair-filled.
The 3p subshell holds only 1 electron — the lone valence p electron that makes Al a metal with +3 oxidation state.
Noble-gas notation replaces the inner filled shells with the nearest noble gas in brackets: [Ne] 3s² 3p¹.
The interactive tabs let you explore the configuration, orbital diagram, and element data separately.

Use cases

Quick reference for chemistry homework or exam review.
Visualize orbital filling order through the s and p blocks.
Understand why aluminium forms a +3 ion by losing its three outermost electrons.
Compare aluminium to other Group 13 (IIIA) post-transition metals.
Learn how the 3p¹ configuration explains aluminium's reactivity and bonding.
Teaching aid for introductory atomic structure and periodic trends lessons.
Verify quantum numbers for each of aluminium's 13 electrons.

Frequently Asked Questions

Last updated: 2026-07-08 · Reviewed by Nham Vu