One interesting fact regarding the chemical element argon is that an estimated 65 trillion metric tons of argon is present in Earth's atmosphere, as claimed by one of the element's discover, Lord Rayleigh. Argon was jointly discovered in 1894 by Scottish chemist William Ramsay and English physicist John William Strut, otherwise known as Lord Rayleigh.
Argon derived its name from the Greek term "argos," which means "inactive," "lazy" or "idle." Its non-reactive nature was first detected by Sir Henry Cavendish, although this inherent property also hindered him from fully separating the element from the various components of air. The first noble gas to be discovered, scientists have found no biological role for argon. It is primarily used to as a protective layer in incandescent light bulbs to prevent corrosion of the filament. A blue-green color is radiated when argon is utilized as a gas laser.
In 1957, argon's chemical symbol was changed from "A" to "Ar" by the International Union of Pure and Applied Chemists. It shares this distinction with the element mendelevium, which was modified from "Mv" to "Md."
The most abundant naturally occurring isotope of argon is argon-40, comprising more than 99 percent of the planet's argon supply. This results from the radioactive decay of potassium-40, with the levels of argon-40 continually rising as the earth ages. The radioactive decay of potassium into argon is currently being used in geologic precision dating.