What is the electron configuration of phosphorus?

Phosphorus (P, Z=15) has the ground-state electron configuration 1s² 2s² 2p⁶ 3s² 3p³. Its 15 electrons fill five subshells across three principal shells.

What is the noble-gas shorthand for phosphorus?

The condensed notation is [Ne] 3s² 3p³, where [Ne] represents the filled 1s² 2s² 2p⁶ core shared with neon.

How many valence electrons does phosphorus have?

Phosphorus has 5 valence electrons: 2 in the 3s subshell and 3 in the 3p subshell. This matches its Group 15 (VA) membership.

Why does phosphorus have three half-filled 3p orbitals?

Hund's rule states that electrons occupy separate orbitals of equal energy before pairing up. With 3 electrons in the 3p subshell, each of the three 3p orbitals holds exactly one unpaired electron, giving a half-filled subshell with relatively high stability.

What oxidation states does phosphorus form?

Phosphorus most commonly shows −3 (gaining 3 electrons, as in PH₃), +3 (losing 3p electrons, as in PCl₃), and +5 (losing all 5 valence electrons, as in PCl₅ or H₃PO₄). The +5 state uses the empty 3d orbitals for expanded octet bonding.

What block and period is phosphorus in?

Phosphorus is in Period 3, Group 15 (VA), and belongs to the p-block of the periodic table.

Is phosphorus the same as nitrogen in terms of configuration?

Both are Group 15 elements with three half-filled p orbitals (nitrogen: 1s² 2s² 2p³; phosphorus: 1s² 2s² 2p⁶ 3s² 3p³). Phosphorus adds a filled 2p subshell and a 3s² core relative to nitrogen, placing it in the third period.

Phosphorus Electron Configuration

Name: Phosphorus Electron Configuration
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Interactive reference for phosphorus's electron configuration (1s² 2s² 2p⁶ 3s² 3p³), orbital box diagram, quantum numbers, and key atomic properties.

Z = 15 P Phosphorus

Phosphorus — Electron Configuration

Atomic number 15 · Nonmetal · Period 3, Group 15 · p-block

1s² 2s² 2p⁶ 3s² 3p³ [Ne] 3s² 3p³ 15 electrons 5 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	3	6	3p³
Total		15

Full Configuration

1s² 2s² 2p⁶ 3s² 3p³

All subshells written explicitly.

Noble-Gas Shorthand

[Ne] 3s² 3p³

[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 3p³ 5 / 18 electrons (28%)

Shell 3 can hold up to 18 electrons (3s + 3p + 3d). Phosphorus uses 5 of those 18 slots.

Orbital Box Diagram

2 electrons (paired) — filled

6 electrons across 3 orbitals — filled

2 electrons (paired) — filled

3 electrons (one per orbital, all spin up) — Hund's rule

Each box represents one orbital. Opposing arrows show paired electrons with opposite spins (+½ and −½). Phosphorus's three 3p electrons each occupy a separate orbital before any pairing occurs — this is Hund's rule, giving a half-filled 3p³ subshell.

Quantum Numbers for All 15 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
14	3	1	0	+½	3p
15	3	1	1	+½	3p

n = principal quantum number; l = azimuthal (l=0 → s, l=1 → p); mₗ = magnetic; mₛ = spin. Electrons 13–15 each occupy a distinct 3p orbital with mₛ = +½ per Hund's rule.

Summary

Interactive reference for phosphorus's electron configuration (1s² 2s² 2p⁶ 3s² 3p³), orbital box diagram, quantum numbers, and key atomic properties.

How it works

The Aufbau principle fills orbitals from lowest to highest energy.
Phosphorus's 15 electrons occupy five subshells: 1s, 2s, 2p, 3s, and 3p.
The 2p subshell holds 6 electrons across three orbitals, each pair-filled.
The 3p subshell holds 3 electrons — one per orbital with spin up, following Hund's rule.
Noble-gas notation replaces the inner filled shells with the nearest noble gas in brackets: [Ne] 3s² 3p³.
The tabs below let you explore the full configuration, orbital diagram, and element data separately.

Use cases

Quick reference for chemistry homework or exam review on p-block elements.
Visualize Hund's rule in action: three half-filled 3p orbitals in phosphorus.
Understand why phosphorus commonly forms −3, +3, and +5 oxidation states.
Compare phosphorus to neighboring elements silicon and sulfur in Period 3.
Teaching aid for introductory atomic structure and electron configuration lessons.
Verify quantum numbers for each of phosphorus's 15 electrons.
Explore how the half-filled 3p³ configuration contributes to phosphorus's stability.

Frequently Asked Questions

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