Argon (Ar) is a colorless, odorless, monatomic, highly unreactive gaseous element, which is the third most abundant gas in the Earth's atmosphere (making up approximately 1 percent of the atmosphere). It is obtained commercially by fractionation of liquid air. Argon is the most abundant of the noble gases (inert gases); it makes up 0.93% of the atmosphere by volume, and 99.6% of this is the isotope 40Ar, the remainder being 36Ar (0.34%) and 38Ar (0.06%). It is used in electric light bulbs, fluorescent tubes, electronic valves, argon lasers, and as an inert-gas shield in arc-welding. Argon has no known true compounds.
|relative atomic mass||39.948|
|first ionization energy||1521 kJ/mol|
|atomic radius||95 pm|
|melting point||-189.4°C (-308.9°F)|
|boiling point||-185.9°C (-302.6°F)|
Argon beam coagulator ablation is a procedure that destroys tissue with an electrical current passed through a stream of argon gas to the tissue. It is used to treat endometriosis and other conditions, and to stop blood loss during surgery.