Argon
Argon (Ar) is an inert gas of the noble gases (group 18). It is colourless, odourless and inert to other substances. It makes up 0.94% of the Earth’s atmosphere, the third most abundant atmospheric gas, with levels increasing gradually because radioactive potassium-40 turns into argon as it decays. Argon is 1.38 times heavier than air and can be obtained through the distillation of liquid air.
It has a number of uses but is well know as an infill gas for double glazed units, where because of its density it improves thermal performance. It is generally accepted that the argon will normally leak from the unit at a rate of 1% each year, or more if the seals degrade or break.
Other uses of argon include the production of titanium and other reactive elements as it creates an inert environment preventing oxidisation and potential corrosion. Fluorescent tubes and low-energy bulbs also make use of argon with an electric discharge passing through the gas, generating UV light, the bulbs coating on the inside is activated by UV light and glows brightly.
It was unwittingly isolated in the late 1700's and mistaken for unreactive air but wasn't fully discovered until the late 1800's when Lord Rayleigh and William Ramsay separated it from liquid air. Today Germany is the lead exporter of Argon, followed by Belgium, the Netherlands and China. The manufacture and use of argon creates minimal health risks, although an asphyxiant only in large volumes when it might become hazardous. The gas dissipates into the air under normal conditions and is not harmful to plant, animal or aquatic life.
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