Symbol: O
Atomic number: 8
Atomic mass: 15.9994
Group: Non-Metal
CAS-number: 7782-44-7

Physical data
Other info
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Physical data

Electronic data

Shells: 2, 6
Orbitals: [He] 2s2 2p4
Electronegativity: 3.5, 3.5
1. Ionization potential: 13.6181 eV
2. Ionization potential: 35.117 eV
3. Ionization potential: 54.934 eV
Oxidation states: -2, -1
Electrical conductivity: --

Thermal data

Melting point: -218.4 °C
Boiling point: -182.962 °C
Specific heat: 0.92 J/gK
Heat of fusion: 0.22259 kJ/mol
Heat of vaporization: 3.4099 kJ/mol
Thermal conductivity: 0.0002674 W/cmK

Steric data

Atomic radius: 0.65 Å
Ionic radius: 1.40 Å (-2)
Covalent radius: 0.73 Å
Atomic volume: 14.0 cm³/mol
Density (293 K): 0.001429 g/cm³
Crystal structure: cubic


NuclideAbundance [%]MassSpinHalflifeDecay modeDecay tree
15O 0 15 1/2 122.2s β+, EC View
16O 99.759 15.9949 0 -- --
17O 0.037 16.9991 5/2 -- --
18O 0.204 17.9992 0 -- --

Other info

Name origin:Greek: oxys and genes, (acid former)
Description:Colorless, odorless, tasteless gas; pale blue liquid. Third most abundant element in the universe. It is the most abundant element in the earth's crust, and makes up almost 21% of the atmosphere.
Discovered by:Joseph Priestly, Carl Wilhelm Scheele
Sources:Obtained primarily from liquid air by fractional distillation. Small amounts are made in the laboratory by electrolysis of water or heating potassium chlorate (KClO3) with manganese dioxide (MnO2) catalyst.
Use(s):Used in steel making, welding, and supporting life. Naturally occuring ozone (O3) in the upper atmosphere shields the earth from ultraviolet radiation.