The molecular formula for argon gas is Ar. Argon exists as a gas at room temperature, so its chemical symbol is the molecular formula for argon gas.
Argon was discovered in 1894 by Lord Rayleigh and Sir William Ramsay. The two scientists isolated the gas from a sample of clean air. The gas is found naturally in the atmosphere and comprises approximately 1 percent of the Earth's atmosphere. On the periodic table, Argon is found in period 8 and is a part of the noble gas group. It also has an atomic number of 18 and is considered to be completely inert.