argonatomen

Argon atoms refer to the chemical element argon, symbol Ar, and atomic number 18. Argon is a noble gas in the third period of the periodic table. It is colorless, odorless, and highly unreactive under ordinary conditions. In its ground state, argon has the electronic configuration [Ne] 3s2 3p6, giving it a complete outer shell and making it a monoatomic gas at room temperature. Its melting point is about -189.3 °C and its boiling point about -185.8 °C.

Argon is present in Earth’s atmosphere at roughly 0.93% by volume, making it the third most abundant atmospheric gas after nitrogen and oxygen. It is extracted commercially mainly by fractional distillation of liquid air and is often produced during the industrial separation of oxygen and nitrogen.

The most common isotope of argon is argon-40; other stable but less abundant isotopes include argon-36 and argon-38. Argon-40 arises from the radioactive decay of potassium-40 and is central to argon–argon dating, a radiometric dating method used in geochronology and archaeology.

Applications for argon are broad due to its inertness. It is used as a shielding gas in arc welding and in the production and processing of metals and crystals. It fills incandescent and fluorescent lamps and is employed in ion lasers (argon ion lasers) and other optical devices. Argon is also used to provide an inert atmosphere in high-temperature processes and in double-glazed windows to reduce heat transfer. Argon was identified as a separate element in 1894 by Lord Rayleigh and William Ramsay, and its name derives from the Greek argos, meaning inactive.