Oxygen Electron Configuration

Explore oxygen's electron configuration 1s² 2s² 2p⁴, its orbital box diagram, quantum numbers, and shell diagrams for any element by atomic number.

Use the Oxygen Electron Configuration

8

Element 8 — Oxygen

1s² 2s² 2p&sup4;

Noble-gas notation: [He] 2s² 2p&sup4; • 6 valence electrons

Electron Configuration Notations

Full spdf Notation 1s² 2s² 2p&sup4;
Noble-Gas Shorthand [He] 2s² 2p&sup4;
Subshell Breakdown
1s² 2s² 2p&sup4;
Valence Shell 2s² 2p&sup4; (6 electrons, n=2)
Core Electrons 1s² (2 electrons, [He] core)
Unpaired Electrons 2 (in 2py, 2pz)
One step past half-filled: Nitrogen's 2p subshell is exactly half-filled (3 electrons, extra stable). Oxygen adds one more electron, which must pair in the 2px orbital. This pairing slightly destabilizes the 2p subshell relative to nitrogen, which is why oxygen's first ionization energy is actually lower than nitrogen's despite having more protons.

Summary

Oxygen (atomic number 8) has the ground-state electron configuration 1s² 2s² 2p⁴. Its four 2p electrons partially fill the three available p orbitals: two orbitals hold one electron each (spin-up), and one orbital holds a paired set (spin-up and spin-down), following Hund's rule. The tool shows the full spdf notation, noble-gas shorthand [He] 2s² 2p⁴, an orbital box diagram, and a quantum-number table for all eight electrons. An interactive explorer lets you enter any atomic number from 1 to 36 to see that element's ground-state configuration and shell diagram.

How it works

  1. Oxygen has 8 protons, so the neutral atom has 8 electrons.
  2. Electrons fill orbitals from lowest to highest energy following the Aufbau principle: 1s → 2s → 2p.
  3. The first two fill 1s, the next two fill 2s, and the remaining four enter the 2p subshell.
  4. Hund's rule: the first three 2p electrons each occupy a separate orbital (spin-up), then the fourth must pair in the 2px orbital (spin-down).
  5. Use the tabs to switch between notations, the orbital box diagram, quantum numbers, and the element explorer.
  6. In the Element Explorer tab, enter any atomic number 1–36 to see the electron configuration and shell population.

Use cases

  • Review oxygen's electron configuration for a chemistry exam.
  • Understand why oxygen has 2 unpaired electrons and forms 2 covalent bonds.
  • Look up the four quantum numbers (n, l, mℓ, mΰ) for each of the 8 electrons.
  • Compare the full spdf notation to the noble-gas shorthand [He] 2s² 2p⁴.
  • Explore shell diagrams for any element from hydrogen to krypton.
  • Teach orbital filling order and Hund's rule with an interactive diagram.
  • Explain why oxygen is more electronegative than nitrogen due to its added proton and paired 2p electron.

Frequently Asked Questions

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