The molecular weight of argon is 39.9 grams/mole. It has a chemical symbol Ar and an atomic number of 18. The element is found in group number 18 and in period number 3 on the periodic table.
Argon is a colorless gas that is found in the atmosphere in very low concentrations. It is an inert element and is one of the noble gases on the periodic table. Argon was discovered in 1894 by Sir William Ramsay and Lord Rayleigh. It was first isolated from a sample of clean air and was obtained by removing nitrogen, oxygen, water and carbon dioxide from the sample.