Chemical element · Atomic number 8
Oxygen
Oxygen in the periodic table: atomic number 8, electron configuration, atomic mass, physical data, oxidation states, media credit and visible sources.
Nonmetal
gaseous
15.999 u
Documented element sampleA labelled oxygen ampoule; the colorless gas is not visible through the glass.
Image credit: James St. John
Auto-oriented, limited to 1600 × 1200 pixels and re-encoded as WebP; the subject was not altered.
Atomic classification
Shell occupancy
Oxygen in the Bohr shell model
This shows the electron distribution of the neutral atom in a simplified shell model.
- K · n=1
- 2 electrons
- L · n=2
- 6 electrons
- Electron configuration
- [He]2s2 2p4
- Electrons per shell
- 2 · 6
- Group
- 16
- Period
- 2
- Block
- P
- Element category
- Nonmetal
Physical and chemical properties
- Atomic mass
- 15.999 u
- Standard state
- gaseous
- Density
- 0.001429 g/cm³
- Melting point
- 54.36 K
- Boiling point
- 90.2 K
- Electronegativity
- 3.44 (Pauling)
- First ionisation energy
- 13.618 eV
- Oxidation states
- -2
- Discovery
- 1774
Safety and periodic classification
Safety
Safe handling cannot be inferred from Oxygen's position in the periodic table alone. Laboratory, classroom and disposal decisions must follow the documentation for the exact material and its safety data sheet.
Position and comparison
Oxygen is in period 2, group 16 and the P block. Its direct neighbours by atomic number are Nitrogen and Fluorine. The recorded Pauling electronegativity is 3.44. Periodic trends are compared only through the separately sourced neighbouring values.
Sources and scope
PubChem attributes element data to sources including IUPAC, NIST and IAEA. Quanta stores the referenced snapshot locally and leaves unknown values unavailable.
Where Oxygen sits among the 118 elements
The table compares the reported values for Oxygen with every other element that carries the same value in the snapshot. A rank is not a judgement, it is orientation: it says how unusual this value is across the periodic table.
| Value | Oxygen | Position in the data set |
|---|---|---|
| Melting point | 54.36 K | Rank 99 of 103 elements with a reported value. Highest: Carbon. |
| Boiling point | 90.2 K | Rank 87 of 93 elements with a reported value. Highest: Rhenium. |
| Density | 0.001 g/cm³ | Rank 92 of 96 elements with a reported value. Highest: Osmium. |
| Electronegativity (Pauling) | 3.44 | Rank 2 of 95 elements with a reported value. Highest: Fluorine. |
| Ionisation energy | 13.618 eV | Rank 7 of 102 elements with a reported value. Highest: Helium. |
All values and ranks come from the PubChem Periodic Table snapshot, retrieved on 2026-07-15. Elements without a reported value are excluded, so the population differs per row.
The neighbours of Oxygen in the periodic table
- Place in the table
- Group 16, period 2, P block. Classified as nonmetal, gaseous at standard conditions.
- Direct neighbours
- Atomic number 8. Preceded by Nitrogen, followed by Fluorine.
- Same group
- Same number of outer electrons, and therefore similar reactivity to Sulfur, Selenium, Tellurium, Polonium, Livermorium.
- Discovery
- Recorded in the snapshot as: 1774. Who, where and under what circumstances is not part of that record, so this page carries the sourced year and no discovery narrative.
- Oxidation states
- -2. They follow from the electron configuration [He]2s2 2p4 and indicate which compounds to expect.
Go from looking up chemistry to remembering it.
Turn your notes into source-backed study cards and review them at the right time.
Starter stays free · no payment details