All practice pages/Interatomic theory/Elements
Element 10, a noble gas
The gas that glows red-orange in a sign tube, and one of the least reactive substances there is.
Period 2, group 18. The other noble gases are tinted, and every cell opens its own article.
A full valence shell, so it has almost no tendency to gain, lose or share electrons, and it exists as single atoms.
About 18 parts per million of air. It is the fifth most abundant element in the universe but rare on Earth, because as a light, unreactive gas it escaped into space while the planet formed. All of it is collected as a byproduct of separating liquid air into oxygen and nitrogen.
William Ramsay and Morris Travers found it in 1898 by slowly boiling liquid air and examining each fraction; it glowed crimson in their spectrum tube. Ramsay's 13-year-old son suggested the Latin novum, new, and they chose the Greek neos instead.
Neon signs, though only the red-orange ones are pure neon; other colors come from argon, mercury vapor and colored glass or coatings. Neon also goes into the lasers that print patterns on computer chips, helium-neon lasers, high-voltage indicators and, as a liquid, cryogenic cooling.