It is in group 18 ( noble gases ) of the periodic table.

Argon became the first member of the noble gases to be discovered.

Allotropes are typically more noticeable in non-metals ( excluding the halogens and the noble gases ) and metalloids.

All but a few of the most inert elements, such as noble gases and noble metals, are usually found on Earth in chemically combined form, as chemical compounds.

The version of this classification used in the periodic tables presented here includes: actinides, alkali metals, alkaline earth metals, halogens, lanthanides, post-transition metals ( or " other metals "), metalloids, noble gases, nonmetals ( or " other nonmetals "), and transition metals.

Similarly, the halogens and the noble gases are nonmetals, viewed in the broader sense.

Elements are trying to reach the low-energy noble gas configuration, and therefore alkali metals and halogens will donate and accept one electron, respectively, and the noble gases themselves are chemically inactive.

The noble gases do not form diatomic molecules: this can be explained using molecular orbital theory ( see molecular orbital diagram ).

* Article about helium and other noble gases

Typically, the stable electron configuration is one of the noble gases for elements in the s-block and the p-block, and particular stable electron configurations for d-block and f-block elements.

The noble gases make a group of chemical elements with similar properties: under standard conditions, they are all odorless, colorless, monatomic gases with very low chemical reactivity.

The six noble gases that occur naturally are helium ( He ), neon ( Ne ), argon ( Ar ), krypton ( Kr ), xenon ( Xe ), and the radioactive radon ( Rn ).

For the first six periods of the periodic table, the noble gases are exactly the members of group 18 of the periodic table.

The properties of the noble gases can be well explained by modern theories of atomic structure: their outer shell of valence electrons is considered to be " full ", giving them little tendency to participate in chemical reactions, and it has been possible to prepare only a few hundred noble gas compounds.

The noble gases have also been referred to as inert gases, but this label is deprecated as many noble gas compounds are now known.

In 1902, having accepted the evidence for the elements helium and argon, Dmitri Mendeleev included these noble gases as group 0 in his arrangement of the elements, which would later become the periodic table.

Radon was first identified in 1898 by Friedrich Ernst Dorn, and was named radium emanation, but was not considered a noble gas until 1904 when its characteristics were found to be similar to those of other noble gases.

Although argon is a noble gas, it has been found to have the capability of forming some compounds.

The " inert " or noble chemical elements ( helium, neon, argon, krypton, xenon and radon ) are composed of lone atoms as their smallest discrete unit, but the other isolated chemical elements consist of either molecules or networks of atoms bonded to each other in some way.

In 1895, French chemist Henri Moissan attempted to form a reaction between fluorine, the most electronegative element, and argon, one of the noble gases, but failed.

* The addition of a small amount of noble gas ( such as helium, argon, or xenon ) to the gas in the bubble increases the intensity of the emitted light.

An important factor is that the bubble contains mainly inert noble gas such as argon or xenon ( air contains about 1 % argon, and the amount dissolved in water is too great ; for sonoluminescence to occur, the concentration must be reduced to 20 – 40 % of its equilibrium value ) and varying amounts of water vapor.

The light emission of highly compressed noble gas is exploited technologically in the argon flash devices.

Sir William Ramsay ( 1852 – 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 Lord Rayleigh who received the Nobel Prize in Physics that same year for the discovery of argon ).

First, argon is abundant ( in the atmosphere, as a result of the radioactive decay of potassium ) and therefore cheaper than other noble gases.

It has the electron configuration of a noble gas ( argon ).

* The noble gases, viz., helium, neon, argon, xenon, krypton, and radon, show a non-expected behavior when exposed to this new element.

Lecoq contributed more to the development of the periodic classification of elements by proposing, soon after its discovery, that argon was a member of a new, previously unsuspected, chemical series of elements, later to become known as the noble gases.

Earth's atmosphere contains roughly ( by molar content / volume ) 78. 08 % nitrogen, 20. 95 % oxygen, a variable amount ( average around 1. 247 %) water vapor, 0. 93 % argon, 0. 038 % carbon dioxide, and traces of hydrogen, helium, and other " noble " gases.

Gaseous scintillators consist of nitrogen and the noble gases helium, argon, krypton, and xenon, with helium and xenon receiving the most attention.

These occur for the noble gases helium, neon, argon, krypton, xenon, and radon.

An excimer laser typically uses a combination of a noble gas ( argon, krypton, or xenon ) and a reactive gas ( fluorine or chlorine ).

The new order agrees with the chemical properties of these elements, since argon is a noble gas and potassium is an alkali metal.

A violet wand electrode is usually made of clear tempered glass which is sealed and evacuated and backfilled with a noble gas, typically argon and sometimes neon, in a process similar to the manufacturing of neon signs.

An electric glow discharge is a plasma formed by the passage of current at 100 V to several kV through a gas, often argon or another noble gas.

Although many variations exist, a plasma lamp is usually a clear glass sphere filled with a mixture of various gases ( most commonly neon, sometimes with other noble gases such as argon, xenon and krypton ) at nearly atmospheric pressure.

* Sputtering relies on a plasma ( usually a noble gas, such as argon ) to knock material from a " target " a few atoms at a time.

However, under conditions of low atmospheric pressure ( such as in high-altitude aircraft ), or in an environment of noble gas such as argon, neon, etc., sparks will appear at much lower voltages.

In 1962 Neil Bartlett discovered the first chemical compound of a noble gas, xenon hexafluoroplatinate .< ref name =" bartlett "> Compounds of other noble gases were discovered soon after: in 1962 for radon, radon difluoride, and in 1963 for krypton, krypton difluoride ().

The heavier noble gases ( krypton, xenon ) are the rarest stable elements on Earth.

This is because noble gases such as xenon and krypton are highly inert and do not usually form chemical compounds.

Of the noble gasses, radon is radioactive, helium escapes through the glass relatively quickly, and krypton is quite expensive.

The gas used in krytrons is hydrogen ; noble gases ( usually krypton, or a Penning mixture ) can also be used.

Under hyperbaric conditions ( pressures above normal atmospheric pressure ), other gases such as nitrogen, and noble gases such as argon, krypton, and xenon become anaesthetics.

The definition of gives zero-value for the noble gases argon, krypton, and xenon.

An excimer laser typically uses a mixture of a noble gas ( argon, krypton, or xenon ) and a halogen gas ( fluorine or chlorine ), which under suitable conditions of electrical stimulation and high pressure, emits coherent stimulated radiation ( laser light ) in the ultraviolet range.

The formation of endohedral complexes with helium, neon, argon, krypton and xenon as well as numerous adducts of the He @ C < sub > 60 </ sub > compound was also demonstrated with pressures of 3 kbars and incorporation of up to 0. 1 % of the noble gases.

For example, the solid noble gas krypton can be used to form an inert matrix within which a reactive F < sub > 3 </ sub >< sup >-</ sup > ion can sit in chemical isolation.