Barium Electron Configuration

Interactive reference for barium's electron configuration (1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d¹⁰ 5s² 5p⁶ 6s²), orbital diagram, quantum numbers, and key properties.

Use the Barium Electron Configuration

Z = 56 Ba Barium

Barium — Electron Configuration

Atomic number 56 · Alkaline earth metal · Period 6, Group 2 · s-block

[Xe] 6s² 56 electrons 2 valence e⁻ +2 oxidation state

Subshell Breakdown

Subshell Type Electrons 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 6 6 5p⁶
6s s orbital, shell n=6 2 2 6s²
Total 56

Full Configuration

1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d¹⁰ 5s² 5p⁶ 6s²

All 12 subshells written explicitly — 56 electrons total.

Noble-Gas Shorthand

[Xe] 6s²

[Xe] = 1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d¹⁰ 5s² 5p⁶ (54 electrons).

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 5p⁶ 8 / 50 electrons (16%)
Shell 6 (n=6) — 6s² 2 / 72 electrons (3%)

Shell 4 can hold 32 electrons (4s + 4p + 4d + 4f); barium uses 18 of those slots. Shell 6 holds only the 2 valence electrons.

Summary

Barium (Ba) has atomic number 56 and the ground-state electron configuration 1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d¹⁰ 5s² 5p⁶ 6s². The noble-gas shorthand is [Xe] 6s², where [Xe] represents the filled xenon core of 54 electrons. This tool shows a subshell-by-subshell breakdown, an orbital box diagram, a quantum-number table for the two valence electrons, and key physical and chemical data — a quick reference for students, teachers, and anyone studying Group 2 alkaline earth metals.

How it works

  1. The Aufbau principle fills subshells from lowest to highest energy (1s → 2s → 2p → 3s … → 6s).
  2. Barium's 56 electrons fill twelve subshells across six principal shells.
  3. The 3d and 4d subshells each hold 10 electrons — the d-block contribution that sets barium apart from lighter alkaline earth metals.
  4. The outermost subshell is 6s², giving barium 2 valence electrons and a typical +2 oxidation state.
  5. Noble-gas notation compresses the inner 54 electrons into [Xe], leaving only the valence 6s² exposed.
  6. The three tabs let you explore the subshell table, orbital box diagram, and element facts separately.

Use cases

  • Quick reference for chemistry homework or exam prep on Period 6 elements.
  • Visualize how the d-block fills before the 6s subshell in heavier alkaline earth metals.
  • Understand why barium always forms a +2 ion by losing both 6s electrons.
  • Compare barium to lighter Group 2 members — magnesium, calcium, strontium — to see periodic trends.
  • Study how the xenon noble-gas core stabilizes barium's inner electron structure.
  • Teaching aid for introductory atomic structure, periodic trends, and s-block chemistry lessons.
  • Verify quantum numbers for barium's two valence electrons.

Frequently Asked Questions

Last updated: 2026-09-30 · Reviewed by Nham Vu