Neon Ne

Discovery

After William Ramsay and Lord Rayleigh discovered argon in 1894 and Ramsay found helium on Earth in 1895, it was clear that a whole family of unreactive gases was missing from the periodic table. In 1898 Ramsay and his assistant Morris Travers obtained large quantities of liquefied air, let it evaporate slowly and collected the fractions that boiled off at different temperatures.

In a matter of weeks they identified three new elements: krypton, neon and xenon. When they placed the neon fraction in a discharge tube, it produced a blaze of crimson light unlike anything they had seen, and its spectrum confirmed a new element.

Neon became a commercial product thanks to the French engineer Georges Claude, who developed large-scale air liquefaction and displayed neon lighting in Paris in 1910. Neon advertising signs spread rapidly through Europe and America in the 1920s.

Origin of the name

The name comes from the Greek neos, meaning 'new'. According to a well-known account, Ramsay's young son suggested the Latin novum, and Ramsay adopted the Greek equivalent instead. The symbol is Ne.

Main uses

• Lighting and signs: classic red-orange neon signs contain pure neon; other colours use different gases or coloured phosphor coatings.
• Lasers: helium–neon lasers produce a steady red beam used in barcode scanners, alignment tools and teaching labs. Neon is also the main buffer gas in the excimer lasers used for semiconductor lithography.
• Cryogenics: liquid neon is a refrigerant for temperatures between those of liquid helium and liquid nitrogen.
• Indicators and electronics: small neon lamps serve as indicator lights, and neon is used in some voltage testers and plasma displays.

Isotopes

Neon has three stable isotopes: neon-20 (about 90.5 percent), neon-21 (about 0.3 percent) and neon-22 (about 9.2 percent). The ratios differ between the atmosphere, the solar wind and gases trapped in meteorites and deep mantle rocks, so geochemists use them to trace the origins of volatile elements in the solar system. Neon-21 produced by cosmic rays in surface rocks helps date how long those rocks have been exposed. Neon's radioactive isotopes are all short-lived.

In everyday life

Neon makes up only about 18 parts per million of the air, so it is obtained as a by-product of large air separation plants. It is non-toxic and chemically inert; the only hazard is that, like any inert gas, it can displace oxygen in a confined space.

Many signs called 'neon' actually contain argon with a little mercury, which gives blue light, or are now made with LEDs.