Neon is a chemical element with the symbol Ne and atomic number 10. It is a noble gas, which means it is chemically inert and does not form compounds. Neon is a colorless, odorless, and tasteless gas under standard conditions, with about two-thirds the density of air. It was discovered in 1898 as one of the three residual rare inert elements remaining in dry air, after nitrogen, oxygen, argon, and carbon dioxide were removed. Neon is the second-lightest noble gas, after helium, and glows reddish-orange in a vacuum discharge tube.
Neon is present in the Earths atmosphere at a concentration of just 18 parts per million. It is more abundant in the cosmos than on Earth. The largest use of neon is in making neon signs for advertising. Neon signs emit a bright orange-red light when an electrical current is passed through them. Neon is also used to make high-voltage indicators, switching gear, lightning arresters, diving equipment, and lasers. Gas lasers are made with the help of neon and helium. Additionally, neon is used in cryogenic refrigeration, where it has more than 40 times the refrigerating capacity per volume than liquid helium and more than three times that of liquid hydrogen.
