Antimony Electron Configuration

Reference for antimony's electron configuration ([Kr] 4d¹⁰ 5s² 5p³), orbital box diagram, valence electrons, and key atomic data for Sb (Z=51).

Z = 51 Sb Antimony

Antimony — Electron Configuration

Atomic number 51 · Metalloid (pnictogen) · Period 5, Group 15 · p-block

1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d¹⁰ 5s² 5p³ [Kr] 4d¹⁰ 5s² 5p³ 51 electrons 5 valence e⁻ Half-filled 5p³

Half-Filled 5p³ — Hund's Rule Stability

Antimony's three 5p electrons each occupy a separate orbital with parallel spins (mₗ = −1, 0, +1). This half-filled 5p³ arrangement minimizes electron–electron repulsion and gives moderate extra stability — the same pattern as nitrogen (2p³) and phosphorus (3p³) in Group 15.

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 6 6 3p⁶
3d d orbitals, shell n=3 10 10 3d¹⁰
4s s orbital, shell n=4 2 2 4s²
4p p orbitals, shell n=4 6 6 4p⁶
4d d orbitals, shell n=4 10 10 4d¹⁰
5s s orbital, shell n=5 2 2 5s²
5p p orbitals, shell n=5 (half-filled) 3 6 5p³
Total 51

Full Configuration

1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d¹⁰ 5s² 5p³

All subshells written explicitly.

Noble-Gas Shorthand

[Kr] 4d¹⁰ 5s² 5p³

[Kr] = 1s²…4p⁶ (krypton's filled core, Z=36).

Valence Shell

5s² 5p³

5 valence electrons. Sb³⁺ loses 5p³; Sb⁵⁺ loses 5s² 5p³.

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 3p⁶ 3d¹⁰ 18 / 18 electrons (100%)
Shell 4 (n=4) — 4s² 4p⁶ 4d¹⁰ 18 / 32 electrons (56%)
Shell 5 (n=5) — 5s² 5p³ 5 / 50 electrons (10%)

Shell 5 can hold up to 50 electrons (5s + 5p + 5d + 5f + 5g). Antimony uses 5 of those slots (5s² 5p³), leaving room for 5p to eventually fill and 5d/5f/5g for heavier elements.

Group 15 Pnictogens — Half-Filled p³ Pattern

Element Z Noble-Gas Configuration Classification
Nitrogen (N) 7 [He] 2s² 2p³ Nonmetal
Phosphorus (P) 15 [Ne] 3s² 3p³ Nonmetal
Arsenic (As) 33 [Ar] 3d¹⁰ 4s² 4p³ Metalloid
Antimony (Sb) 51 [Kr] 4d¹⁰ 5s² 5p³ Metalloid
Bismuth (Bi) 83 [Xe] 4f¹⁴ 5d¹⁰ 6s² 6p³ Post-transition metal

Summary

Reference for antimony's electron configuration ([Kr] 4d¹⁰ 5s² 5p³), orbital box diagram, valence electrons, and key atomic data for Sb (Z=51).

How it works

  1. The Aufbau principle fills subshells from lowest to highest energy. For Period 5 post-transition elements the order is: [Kr core] → 4d → 5s → 5p.
  2. Antimony (Z=51) has 51 electrons: the [Kr] core accounts for 36, the filled 4d¹⁰ adds 10 more (total 46), then 5s² adds 2 (total 48), and finally 5p³ adds the last 3 (total 51).
  3. Hund's rule places one electron in each of the three 5p orbitals (mₗ = −1, 0, +1) with parallel spins before any pairing. This half-filled 5p³ arrangement minimizes electron–electron repulsion.
  4. Noble-gas notation replaces the krypton core (1s²…4p⁶, Z=36) with [Kr], giving the abbreviated form [Kr] 4d¹⁰ 5s² 5p³.
  5. Antimony has 5 valence electrons (5s² 5p³). Losing the three 5p electrons yields Sb³⁺; losing all five valence electrons yields Sb⁵⁺.
  6. The symbol Sb comes from Latin "stibium," the historical name for antimony sulfide (stibnite, Sb₂S₃), used as eye cosmetics in antiquity.

Use cases

  • Quick reference for chemistry homework on p-block elements and pnictogen electron configurations.
  • Understand why antimony's half-filled 5p³ subshell (Hund's rule) provides moderate stability.
  • Learn how Sb³⁺ and Sb⁵⁺ ions form by losing 5p and 5s valence electrons.
  • Visualize orbital filling for Period 5 p-block elements using the orbital diagram.
  • Compare antimony to nitrogen and phosphorus in Group 15 (pnictogens).
  • Study Sb in flame retardant chemistry: Sb₂O₃ acts as a flame-retardant synergist.
  • Teaching aid for Hund's rule, valence electrons, and metalloid chemistry lessons.

Frequently Asked Questions

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