Oxygen

Oxygen is a chemical element, in the periodic table. At standard temperature and pressure, oxygen is found as a gas consisting of two oxygen atoms, chemical formula O₂. This oxygen is an important component of air, produced by plants during photosynthesis and is necessary for animals' respiration.

Atomic symbol	O			Color	colorless
Atomic number	8			Density	0.0001429	g/ml
Group	16 (VI)			Melting point	50.35	K
Period	2			Boiling point	90.18	K
Atomic weight	18.9994	u		Vaporization heat	3.4099	kJ/mol
Bonding radius	0.73	A		Fusion heat	0.22259	kJ/mol
Atomic radius	0.65	A		Specific heat	0.92	J/gK
Ionization Potential	13.618	V		Crystals	cubic
Electronegativity	3.44			Oxide	neutral
Electron configuration	1s2 2s2 2p4			See also Periodic table
Etymology	from Greek oxus (acid) and gennan (generate)

Oxygen was discovered by the Swedish pharmacist Karl Wilhelm Scheele in 1771 and named by him, Antoine Laurent Lavoisier and Joseph Priestly in 1774.

Oxygen comprises about 87% of the oceans (as H₂O, water) and 20% of the atmosphere (as O₂, molecular oxygen, or O₃, ozone). Due to its electronegativity, oxygen easily forms chemical bonds with many other elements (which is the origin of the original definition of oxidation). Famous examples are carbon dioxide (CO₂), alcohols (R-OH) and carbon acids (R-COOH).

Isotopes of oxygen
012 0.40 msec p, 17.338 MeV N-11 12.034417	013 8.58 msec EC, 17.765 MeV N-13 13.024810	014 70.606 sec EC, 5.143 MeV N-14 14.008595	015 122.24 sec EC, 2.753 MeV N-15 15.003065	016        99.762% Stable 15.994915	017          0.038% Stable 16.999131	018          0.200% Stable 17.999160
019 26.91 sec B-, 4.821 MeV F-19 19.003579	020 13.51 sec B-, 3.814 MeV F-20 20.004076	021 3.42 sec B-, 8.109 MeV F-21 21.008654	022 2.25 sec B-, 6.490 MeV F-22 22.009962	023 82 msec B-/B-n, 11.290 F-23/F-22 23.015695	024 61 msec B-/B-n, 11.400 F-24/F-23 24.020397	MASS      abund. Half-life Particle, Energy Decay Product(s) Isotopic Mass

See also combustion -- Oxidation.

Back to Chemistry -- Periodic table

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