Description

Argon is a chemical element with symbol Ar and atomic number *8. It is in group *8 (noble gases) of the periodic table. Argon is the third most common gas in the Earth\'s atmosphere, at 0.*3% (9,**0 ppm), making it approximately *3.8 times as abundant as next most common atmospheric gas, carbon dioxide (**0 ppm), and more than **0 times as abundant as the next most common noble gas, neon (*8 ppm). Nearly all of this argon is radiogenic argon**0 derived from the decay of potassium**0 in the Earth\'s crust. In the universe, argon**6 is by far the most common argon isotope, being the preferred argon isotope produced by stellar nucleosynthesis in supernovas.