Neon is a noble gas element denoted by the atomic symbol, Ne. Its atomic number is 10 and its atomic weight is 20.1797. It is a nearly inert element thought only to react with fluorine. Neon is present in the atmosphere in about 1 part neon per 65,000 parts air.

Neon, meaning "new," was discovered in the late nineteenth century. In the 1890s, the English physicist John William Strutt ( Lord Rayleigh) noticed that nitrogen extracted from the air was always slightly heavier than nitrogen obtained from chemical compounds--a curiosity noted much earlier by Henry Cavendish, but still unexplained. In attempting to combine nitrogen with oxygen in the 1780s, Cavendish had found that he always had a small bubble of gas left over. In 1892 Scottish chemist Sir William Ramsay joined forces with Rayleigh to explore the nature of this mysterious bubble, which turned out to contain all the elements in the group of...