Oxygen

Oxygen, 00O
A transparent beaker containing a light blue fluid with gas bubbles
Liquid oxygen boiling
Oxygen
AllotropesO2, O3 (ozone) and more (see Allotropes of oxygen)
Appearance(O2)
gas: colourless
liquid and solid: pale blue
Standard atomic weight Ar°(O)
[15.9990315.99977][1]
Abundance
in the Earth's crust46%
in the oceans86%
in the solar system1%
Oxygen in the periodic table
Hydrogen Helium
Lithium Beryllium Boron Carbon Nitrogen Oxygen Fluorine Neon
Sodium Magnesium Aluminium Silicon Phosphorus Sulfur Chlorine Argon
Potassium Calcium Scandium Titanium Vanadium Chromium Manganese Iron Cobalt Nickel Copper Zinc Gallium Germanium Arsenic Selenium Bromine Krypton
Rubidium Strontium Yttrium Zirconium Niobium Molybdenum Technetium Ruthenium Rhodium Palladium Silver Cadmium Indium Tin Antimony Tellurium Iodine Xenon
Caesium Barium Lanthanum Cerium Praseodymium Neodymium Promethium Samarium Europium Gadolinium Terbium Dysprosium Holmium Erbium Thulium Ytterbium Lutetium Hafnium Tantalum Tungsten Rhenium Osmium Iridium Platinum Gold Mercury (element) Thallium Lead Bismuth Polonium Astatine Radon
Francium Radium Actinium Thorium Protactinium Uranium Neptunium Plutonium Americium Curium Berkelium Californium Einsteinium Fermium Mendelevium Nobelium Lawrencium Rutherfordium Dubnium Seaborgium Bohrium Hassium Meitnerium Darmstadtium Roentgenium Copernicium Nihonium Flerovium Moscovium Livermorium Tennessine Oganesson


O

S
nitrogenoxygenfluorine
Groupgroup 16 (chalcogens)
Periodperiod 2
Block  p-block
Electron configuration[He] 2s2 2p4
Electrons per shell2, 6
Physical properties
Phase at STPgas (O2)
Melting point54.36 K ​(−218.79 °C, ​−361.82 °F)
Boiling point90.188 K ​(−182.962 °C, ​−297.332 °F)
Density (at STP)1.429 g/L
when liquid (at b.p.)1.141 g/cm3
Triple point54.361 K, ​0.1463 kPa
Critical point154.581 K, 5.043 MPa
Heat of fusion(O2) 0.444 kJ/mol
Heat of vaporization(O2) 6.82 kJ/mol
Molar heat capacity(O2) 29.378 J/(mol·K)
Vapor pressure
P (Pa) 1 10 100 1 k 10 k 100 k
at T (K)       61 73 90
Atomic properties
Oxidation states−2, −1, 0, +1, +2
ElectronegativityPauling scale: 3.44
Ionization energies
  • 1st: 1313.9 kJ/mol
  • 2nd: 3388.3 kJ/mol
  • 3rd: 5300.5 kJ/mol
  • (more)
Covalent radius66±2 pm
Van der Waals radius152 pm
Color lines in a spectral range
Spectral lines of oxygen
Other properties
Natural occurrenceprimordial
Crystal structurecubic
Cubic crystal structure for oxygen
Speed of sound330 m/s (gas, at 27 °C)
Thermal conductivity26.58×10−3  W/(m⋅K)
Magnetic orderingparamagnetic
Molar magnetic susceptibility+3449.0·10−6 cm3/mol (293 K)[2]
CAS Number7782-44-7
History
DiscoveryCarl Wilhelm Scheele (1771)
Named byAntoine Lavoisier (1777)
Isotopes of oxygen
Main isotopes Decay
abun­dance half-life (t1/2) mode pro­duct
15O 0% (extinct)
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122.266 s β+100% 15N
16O 99.8% stable
17O 0.0380% stable
18O 0.205% stable
 Category: Oxygen
| references
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Oxygen is a chemical element. It has the symbol O, on the periodic table and atomic number 8. It is the third most common element in the universe, after hydrogen and helium.

Oxygen is more than a fifth of the Earth's atmosphere by volume. In the air, two oxygen atoms usually join to make dioxygen (O
2
), a colourless gas. This gas is often just called oxygen. It has no taste or smell. It is pale blue when it is liquid or solid.

Oxygen is part of the chalcogen group on the periodic table. It is a very reactive nonmetal. It makes oxides and other compounds with many elements. The oxygen in these oxides and in other compounds (mostly silicate minerals, and calcium carbonate in limestone) makes up nearly half of the Earth's crust, by mass.

Most living things use oxygen in respiration. Many molecules in living things have oxygen in them, such as proteins, nucleic acids, carbohydrates and fats. Oxygen is a part of water, which all known life needs to live. Algae, cyanobacteria and plants make the Earth's oxygen gas by photosynthesis. They use the Sun's light to get hydrogen from water, giving off oxygen.

At the top of the Earth's atmosphere is ozone (O
3
), in the ozone layer. It absorbs ultraviolet radiation, which means less radiation reaches ground level.

Oxygen gas is used for making steel, plastics and textiles. It also has medical uses and is used for breathing when there is no good air (by divers and firefighters, for example), and for welding. Liquid oxygen and oxygen-rich compounds can be used as a rocket propellant.

  1. "Standard Atomic Weights: Oxygen". CIAAW. 2009.
  2. Weast, Robert (1984). CRC, Handbook of Chemistry and Physics. Boca Raton, Florida: Chemical Rubber Company Publishing. pp. E110. ISBN 0-8493-0464-4.

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