Argon fluorohydride (HAr F), a compound of argon with fluorine and hydrogen that is stable below 17 K, has been demonstrated.

Lord Rayleigh's method for the isolation of argon, based on an experiment of Henry Cavendish's.

Nearly all of the argon in Earth's atmosphere is radiogenic argon-40, derived from the decay of potassium-40 in the Earth's crust.

They had determined that nitrogen produced from chemical compounds was one-half percent lighter than nitrogen from the atmosphere. Each observed new lines in the color spectrum of air that did not match known elements. Until 1957, the symbol for argon was "A", but now is "Ar".

The difference was slight, but it was important enough to attract their attention for many months. and air is the primary industrial source of purified argon products.

The name "argon" is derived from the Greek word meaning "lazy" or "inactive", as a reference to the fact that the element undergoes almost no chemical reactions.

The complete octet (eight electrons) in the outer atomic shell makes argon stable and resistant to bonding with other elements.

Argon is the third most abundant gas in the Earth's atmosphere, at 0.934% (9340 ppmv) 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 the most abundant noble gas in Earth's crust, comprising 0.00015% of the crust.Its triple point temperature of 83.8058 K is a defining fixed point in the International Temperature Scale of 1990.Argon is produced industrially by the fractional distillation of liquid air.The atmospheres of Mars, Mercury and Titan (the largest moon of Saturn) contain argon, predominantly as 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.Mendeleev positioned the elements on his periodic table in order of atomic weight, but the inertness of argon suggested a placement before the reactive alkali metal.They concluded that there was another gas in the air mixed in with the nitrogen. 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.