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 | |||||||||||||||||
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Symbol | O | ||||||||||||||||
Atomic number | 8 | ||||||||||||||||
Group | 16 | ||||||||||||||||
Period | 2 | ||||||||||||||||
Block | p | ||||||||||||||||
Element category | Nonmetal | ||||||||||||||||
Physical properties | |||||||||||||||||
Phase at STP | Gas | ||||||||||||||||
Density | 1.429 g/cm3 | ||||||||||||||||
Atomic weight | 15.999 u | ||||||||||||||||
Melting point | 54.36 K -218.79 °C -361.822 °F | ||||||||||||||||
Boiling point | 90.188 K -182.962 °C -297.3316 °F | ||||||||||||||||
Atomic properties | |||||||||||||||||
Electronegativity (Pauling Scale) | 3.44 | ||||||||||||||||
Electron affinity | 140.976 kJ/mol | ||||||||||||||||
Oxidation states | −2, −1, 0, +1, +2 () | ||||||||||||||||
Ionization energies |
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Electron configuration | |||||||||||||||||
Elektronkonfiguration (shorthand) | [He] 2s2 2p4 | ||||||||||||||||
Electron configuration | 1s2 2s2 2p4 | ||||||||||||||||
Electrons per shell | 2, 6 | ||||||||||||||||
History | |||||||||||||||||
Discovered | 1771 | ||||||||||||||||
Discovered by | Carl Wilhelm Scheele | ||||||||||||||||
Named by | Antoine Lavoisier |