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Oxygen (O)

From Wikipedia, the free encyclopediaOxygen 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.

Oxygen in the periodic table

SymbolO
Atomic number8
Group16
Period2
Blockp
Element categoryNonmetal

Physical properties

Phase at STPGas
Density1.429 g/cm3
Atomic weight15.999 u
Melting point54.36 K
-218.79 °C
-361.822 °F
Boiling point90.188 K
-182.962 °C
-297.3316 °F

Atomic properties

Electronegativity (Pauling Scale)3.44
Electron affinity140.976 kJ/mol
Oxidation states−2, −1, 0, +1, +2
()
Ionization energies
11313.9 kJ/mol
2 3388.3 kJ/mol
3 5300.5 kJ/mol
4 7469.2 kJ/mol
5 10989.5 kJ/mol
6 13326.5 kJ/mol
7 71330 kJ/mol
8 84078 kJ/mol

Electron configuration

Elektronkonfiguration (shorthand)[He] 2s2 2p4
Electron configuration1s2 2s2 2p4
Electrons per shell2, 6

History

Discovered1771
Discovered byCarl Wilhelm Scheele
Named byAntoine Lavoisier
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