Neon is a nontoxic, colorless gas that forms no known stable compounds. It is the second lightest noble gas. If placed in a vacuum discharge tube, neon has a reddish-orange glow when an electric current is passed through it.
The name "neon" is derived from the Greek word "neos," which means "new." Discovered by Sir William Ramsey and Morris Travers in 1898, neon has an atomic weight of 20.1797. The fourth most abundant element in the universe, neon is relatively rare on earth, making up 1 part per 65,000 in air. Widely used to make advertising signs, neon can be combined with helium to make gas lasers. It is used to make lightning arrestors and high-voltage indicators as well as television tubes and wave meter tubes. In its liquid state, neon is used as a refrigerant.
Activated charcoal is used to isolate neon. After super-cooling air, the charcoal absorbs the remaining neon and hydrogen. The hydrogen is then removed by adding oxygen, which converts it to water.
Inhalation of concentrated neon can cause dizziness, nausea, vomiting, loss of consciousness and death, and contact with liquid neon can result in frostbite to both skin and eyes. Because of neon's inability to form stable compounds, it poses no threat to the environment.