Argon

Arargon gas 40 Ar 36 argon18Ar + areargon (Ar)argon isotope ratiosargon-40
Argon is a chemical element with the symbol Ar and atomic number 18.wikipedia
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Noble gas

noble gasesrare gas18
It is in group 18 of the periodic table and is a noble gas. Argon-36, in the form of argon hydride (argonium) ions, has been detected in interstellar medium associated with the Crab Nebula supernova; this was the first noble-gas molecule detected in outer space.
The six naturally occurring noble gases are helium (He), neon (Ne), argon (Ar), krypton (Kr), xenon (Xe), and the radioactive radon (Rn).

Atmosphere of Earth

airEarth's atmosphereatmosphere
Argon is the third-most abundant gas in the Earth's atmosphere, at 0.934% (9340 ppmv).
By volume, dry air contains 78.09% nitrogen, 20.95% oxygen, 0.93% argon, 0.04% carbon dioxide, and small amounts of other gases.

Chemical element

elementelementschemical elements
Argon is a chemical element with the symbol Ar and atomic number 18.
For example, atmospheric air is primarily a mixture of nitrogen, oxygen, and argon, and native solid elements occur in alloys, such as that of iron and nickel.

Neon

Neneon gas 21 Ne
It is more than twice as abundant as water vapor (which averages about 4000 ppmv, but varies greatly), 23 times as abundant as carbon dioxide (400 ppmv), and more than 500 times as abundant as neon (18 ppmv). Argon is isolated from air by fractionation, most commonly by cryogenic fractional distillation, a process that also produces purified nitrogen, oxygen, neon, krypton and xenon.
It was discovered (along with krypton and xenon) in 1898 as one of the three residual rare inert elements remaining in dry air, after nitrogen, oxygen, argon and carbon dioxide were removed.

Symbol (chemistry)

symbolchemical symbolchemical symbols
Argon is a chemical element with the symbol Ar and atomic number 18.

Argon compounds

argon compoundcompound of argon
Theoretical calculation predicts several more argon compounds that should be stable but have not yet been synthesized.
Argon compounds, the chemical compounds that contain the element argon, are rarely encountered due to the inertness of the argon atom.

Inert gas

inertinert gasesinert atmosphere
Argon is mostly used as an inert shielding gas in welding and other high-temperature industrial processes where ordinarily unreactive substances become reactive; for example, an argon atmosphere is used in graphite electric furnaces to prevent the graphite from burning.
Purified argon and nitrogen gases are most commonly used as inert gases due to their high natural abundance (78.3% N 2, 1% Ar in air) and low relative cost.

Liquid air

liquified airair liquefactionliquefy the air
Argon is produced industrially by the fractional distillation of liquid air. Argon is produced industrially by the fractional distillation of liquid air in a cryogenic air separation unit; a process that separates liquid nitrogen, which boils at 77.3 K, from argon, which boils at 87.3 K, and liquid oxygen, which boils at 90.2 K. About 700,000 tonnes of argon are produced worldwide every year.
It is often used for condensing other substances into liquid and/or solidifying them, and as an industrial source of nitrogen, oxygen, argon, and other inert gases through a process called air separation.

John William Strutt, 3rd Baron Rayleigh

Lord RayleighRayleighJohn Strutt, 3rd Baron Rayleigh
Argon was first isolated from air in 1894 by Lord Rayleigh and Sir William Ramsay at University College London by removing oxygen, carbon dioxide, water, and nitrogen from a sample of clean air.
Among many honours, he received the 1904 Nobel Prize in Physics "for his investigations of the densities of the most important gases and for his discovery of argon in connection with these studies."

William Ramsay

Sir William RamsayRamsayRamsay Fellow
Argon was first isolated from air in 1894 by Lord Rayleigh and Sir William Ramsay at University College London by removing oxygen, carbon dioxide, water, and nitrogen from a sample of clean air.
Sir William Ramsay (2 October 1852 – 23 July 1916) was a Scottish chemist who discovered the noble gases and received the Nobel Prize in Chemistry in 1904 "in recognition of his services in the discovery of the inert gaseous elements in air" along with his collaborator, John William Strutt, 3rd Baron Rayleigh, who received the Nobel Prize in Physics that same year for their discovery of argon.

Radiogenic nuclide

radiogenicradiogenic heatradiogenic heating
Nearly all of the argon in the Earth's atmosphere is radiogenic argon-40, derived from the decay of potassium-40 in the Earth's crust. The predominance of radiogenic is the reason the standard atomic weight of terrestrial argon is greater than that of the next element, potassium, a fact that was puzzling when argon was discovered.
Other notable nuclides that are partly radiogenic are argon-40, formed from radioactive potassium, and nitrogen-14, which is formed by the decay of carbon-14.

Shielding gas

Ar-O 2 shield gas
Argon is mostly used as an inert shielding gas in welding and other high-temperature industrial processes where ordinarily unreactive substances become reactive; for example, an argon atmosphere is used in graphite electric furnaces to prevent the graphite from burning.
Only two of the noble gases, helium and argon, are cost effective enough to be used in welding.

Xenon

Xexenon monofluorideXenon chloride laser
Argon is isolated from air by fractionation, most commonly by cryogenic fractional distillation, a process that also produces purified nitrogen, oxygen, neon, krypton and xenon.
Since then, many other xenon compounds have been discovered, in addition to some compounds of the noble gases argon, krypton, and radon, including argon fluorohydride (HArF), krypton difluoride (KrF 2 ), and radon fluoride.

Carbon dioxide

CO 2 CO2carbon dioxide (CO 2 )
It is more than twice as abundant as water vapor (which averages about 4000 ppmv, but varies greatly), 23 times as abundant as carbon dioxide (400 ppmv), and more than 500 times as abundant as neon (18 ppmv). Argon was first isolated from air in 1894 by Lord Rayleigh and Sir William Ramsay at University College London by removing oxygen, carbon dioxide, water, and nitrogen from a sample of clean air.
For this reason, other gases such as nitrogen or argon are preferred for this process by professional wine makers.

Atmosphere of Mars

Martian atmosphereatmosphereMars
The atmospheres of Mars, Mercury and Titan (the largest moon of Saturn) contain argon, predominantly as, and its content may be as high as 1.93% (Mars).
It is primarily composed of carbon dioxide (95.32%), molecular nitrogen (2.6%) and argon (1.9%).

Fluorescent lamp

fluorescent lightingfluorescent lightfluorescent
Argon is also used in incandescent, fluorescent lighting, and other gas-discharge tubes.
A fluorescent lamp tube is filled with a gas containing low-pressure mercury vapor and argon, xenon, neon, or krypton.

Argon fluorohydride

HArF
Argon fluorohydride (HArF), a compound of argon with fluorine and hydrogen that is stable below, has been demonstrated.
It is a compound of the chemical element argon.

Octet rule

octetduet ruleoctet (8-electron) rule
The complete octet (eight electrons) in the outer atomic shell makes argon stable and resistant to bonding with other elements.
The argon atom has an analogous 3s 2  3p 6 configuration.

Triple point

triple point of waterhigh pressureTriple Point cell
Its triple point temperature of 83.8058 K is a defining fixed point in the International Temperature Scale of 1990.
Triple-point cells are so effective at achieving highly precise, reproducible temperatures, that an international calibration standard for thermometers called ITS–90 relies upon triple-point cells of hydrogen, neon, oxygen, argon, mercury, and water for delineating six of its defined temperature points.

Potassium

KK + potassium ion
The predominance of radiogenic is the reason the standard atomic weight of terrestrial argon is greater than that of the next element, potassium, a fact that was puzzling when argon was discovered.
Neutral potassium atoms have 19 electrons, one more than the configuration of the noble gas argon.

Nitrogen

NN 2 dinitrogen
Argon was first isolated from air in 1894 by Lord Rayleigh and Sir William Ramsay at University College London by removing oxygen, carbon dioxide, water, and nitrogen from a sample of clean air. Argon is isolated from air by fractionation, most commonly by cryogenic fractional distillation, a process that also produces purified nitrogen, oxygen, neon, krypton and xenon. Argon has approximately the same solubility in water as oxygen and is 2.5 times more soluble in water than nitrogen.
Commercial-grade nitrogen already contains at most 20 ppm oxygen, and specially purified grades containing at most 2 ppm oxygen and 10 ppm argon are also available.

Argonium

argon hydride
Argon-36, in the form of argon hydride (argonium) ions, has been detected in interstellar medium associated with the Crab Nebula supernova; this was the first noble-gas molecule detected in outer space.
Argonium (also called the argon hydride cation, the hydridoargon(1+) ion, or protonated argon; chemical formula ArH + ) is a cation combining a proton and an argon atom.

Hydride

metal hydridemetal hydrideshydrides
Solid argon hydride (Ar(H 2 ) 2 ) has the same crystal structure as the MgZn 2 Laves phase.
Almost all of the elements form binary compounds with hydrogen, the exceptions being He, Ne, Ar, Kr, Pm, Os, Ir, Rn, Fr, and Ra.

Isotopes of argon

argon-40Argon-36Argon-39
Nearly all of the argon in the Earth's atmosphere is radiogenic argon-40, derived from the decay of potassium-40 in the Earth's crust. Argon-36, in the form of argon hydride (argonium) ions, has been detected in interstellar medium associated with the Crab Nebula supernova; this was the first noble-gas molecule detected in outer space.
Argon ( 18 Ar) has 26 known isotopes, from 29 Ar to 54 Ar and 1 isomer ( 32m Ar), of which three are stable ( 36 Ar, 38 Ar, and 40 Ar).

Air separation

cryogenic distillationCryogenic Air Separationseparation of air
Argon is produced industrially by the fractional distillation of liquid air in a cryogenic air separation unit; a process that separates liquid nitrogen, which boils at 77.3 K, from argon, which boils at 87.3 K, and liquid oxygen, which boils at 90.2 K. About 700,000 tonnes of argon are produced worldwide every year.
An air separation plant separates atmospheric air into its primary components, typically nitrogen and oxygen, and sometimes also argon and other rare inert gases.