8Gas
O 15.999 Atomic mass · uNonmetals
Oxygen
Oxygen is a chemical element with symbol O and atomic number 8. It is a member of the chalcogen group on the periodic table and is a highly reactive nonmetal and oxidizing agent that readily forms compounds (notably oxides) with most elements. By mass, oxygen is the third-most abundant element in the universe, after hydrogen and helium.
Discovery 1774 (Carl Wilhelm Scheele)
K2L6
Physical properties
Values for the element in its standard state.
- Density
- 0.001429g/cm³
- Melting point
- 55K
- Boiling point
- 90K
- Atomic radius
- 73pm
- Bonding type
- Diatomic
- Molar heat
- Not available
Inside the atom
Electron arrangement and the energy behind its behavior.
Full electron configuration
1s, 2 electrons; 2s, 2 electrons; 2p, 4 electrons;
[He] represents 2 core electrons. The full view shows them explicitly.
8 electrons Orbital order preserved from source
- Electronegativity
- 3.44Pauling scale
- First ionization energy
- 1,314kJ/mol
- Electron affinity
- 141kJ/mol
- Van der Waals radius
- 152pm
O OxygenAtomic number 8
1,314kJ/mol
Atomic numberGaps indicate unavailable data
About oxygen
- Appearance
- Not recorded
- Discovery
- 1774 (Carl Wilhelm Scheele)
- Data source
- Read the reference
A missing value means it is unavailable in this reference dataset. Values can vary with measurement method and conditions.