Neon | Research & Encyclopedia Articles

Neon

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 inert, or nonreactive, gases.

The first two inert gases identified were argon and helium. Then in 1898, Ramsay enlisted help from Morris Travers (1872-1961), a young British chemist who had recently graduated from University College, London, where Ramsay was teaching. Together they isolated certain fractions of argon that turned out to contain three other inert gases, one of which was neon.

Neon was identified as a new element by spectroscopy, which reveals the gas' characteristic set of spectral lines. Like the rest of the inert gas family, which includes krypton, xenon, and radon as well as argon and helium, neon is colorless, odorless, and tasteless, and resists the formation of compounds with other elements. It occurs naturally in the atmosphere, from which it is produced for commercial purposes, and can be found in trace amounts in natural gas, minerals, and meteorites.

In 1910 Georges Claude (1870-1960), a French chemist and physicist, showed that neon gas glowed with colored light when electricity was discharged in a neon-filled tube. He also invented a means of purifying the gas in the tube using a charcoal filter. Claude soon developed neon tube lighting that could be twisted to form letters and pictures. By the 1920s neon signs had become extremely popular advertising tools, and a modern variation of them is still in use. Since then, neon has found practical application in many other kinds of lamps. Although it is fairly expensive, very little neon is needed for lighting purposes. Fluorescent lamps are often filled with a mixture of neon and other inert gases, and neon has been used in stroboscopic studies.

Neon beacons can be seen for up to 20 mi. (32 km) and are used for airplane guidance. Small neon tubes are used in voltage-testing devices and as indicators on appliances and electronic instrument panels. In industry, neon is a useful low-temperature refrigerant, particularly because it is hard to vaporize. Its cooling temperature range is suitable for certain infrared detectors and lasers. Neon tube devices protect electric motors from overloading in case of a power surge, and the gas is also used in lightning arrestors, electron tubes, and Geiger counters. The most common gas laser uses a mixture of neon and helium.

Experiments have shown that certain properties of neon may also lend themselves to use in special breathing mixtures for space travelers and deep-sea divers. Helium shares these properties, but unlike helium, neon does not distort a person's voice. Also, neon conducts heat less readily, so that a diver would lose less heat to the surrounding water. Another special property of neon is that when liquefied, it is more compact than other liquefied gases. This has important applications for cryogenic refrigerants. In space travel or other cases where compactness is critical, neon could find new uses as a convenient transport and storage fluid. Substantial amounts of neon are already used in physics research for detecting the motion of nuclear particles; neon displays their paths with a trail of sparks as they pass through the detection chamber.