Bromine Electron Configuration

Reference for bromine's electron configuration (1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁵), orbital box diagram, quantum numbers, and key atomic properties.

Use the Bromine Electron Configuration

Z = 35 Br Bromine

Bromine — Electron Configuration

Atomic number 35 · Halogen · Period 4, Group 17 · p-block

1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁵ [Ar] 3d¹⁰ 4s² 4p⁵ 35 electrons 7 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 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 5 6 4p⁵
Total 35

Full Configuration

1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁵

All subshells written explicitly.

Noble-Gas Shorthand

[Ar] 3d¹⁰ 4s² 4p⁵

[Ar] = 1s² 2s² 2p⁶ 3s² 3p⁶ (the filled argon 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 3p⁶ 3d¹⁰ 18 / 18 electrons (100%)
Shell 4 (n=4) — 4s² 4p⁵ 7 / 32 electrons (22%)

Shell 4 can hold up to 32 electrons (4s + 4p + 4d + 4f). Bromine uses only 7 of those slots.

Summary

Bromine (Br) has atomic number 35 and the ground-state electron configuration 1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁵. This tool displays its full orbital diagram, subshell-by-subshell breakdown, and noble-gas shorthand ([Ar] 3d¹⁰ 4s² 4p⁵), along with a quantum-number summary for its 35 electrons and key physical and chemical properties. It is a reliable reference for students and educators studying atomic structure and periodic-table chemistry.

How it works

  1. The Aufbau principle fills orbitals from lowest to highest energy.
  2. Bromine's 35 electrons fill eight subshells: 1s, 2s, 2p, 3s, 3p, 4s, 3d, and 4p.
  3. The 3d subshell holds 10 electrons across five orbitals, each pair-filled.
  4. The 4p subshell holds 5 electrons — two orbitals are pair-filled and one holds a single unpaired electron.
  5. Noble-gas notation replaces the inner filled shells with argon in brackets: [Ar] 3d¹⁰ 4s² 4p⁵.
  6. 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 halogens.
  • Visualize why bromine has 7 valence electrons and forms a −1 oxidation state.
  • Understand why bromine is one electron short of the noble gas krypton.
  • Compare bromine to neighboring elements selenium and krypton in Period 4.
  • Teaching aid for introductory atomic structure and d-block filling lessons.
  • Verify that 3d fills before 4p per the Aufbau principle.
  • Explore how the 4p⁵ configuration drives bromine's strong oxidizing character.

Frequently Asked Questions

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