The atomic number is 18 and it has a mass number of 39.948. It is in period 3 and group 18. Argon is a noble gas. It's state of matter is a gas and is a non metal.
Argon is used by welders to protect the weld area.
Low-Energy Light Bulbs
Argon stops the filament burning away because it is unreactive.
Double Glazed Windows
Argon is naturally present in air, but when used on its own to fill windows it helps retain more heat than using air.