Neon

Category: noble gas Atomic number: 10 Colour: colourless Melting point: −249°C (−415°F) Boiling point: −246°C (−411°F) First identified: 1898

Neon is a great example of the way that Mendeleev’s periodic table inspired chemists to search for elements they might not otherwise have been alerted to. Sir William Ramsay had already discovered other members of the group of noble gases (also known as the inert gases, due to their lack of reactivity), including helium, argon and krypton (see here, here and here), but the periodic table predicted another member in the spot vertically between helium and argon.

Working with his colleague Morris Travers at University College in London, Ramsay continued to search for the missing element. Having previously isolated argon, they now took a lump of solid argon, and surrounded this with liquid air – the argon evaporated slowly in low pressure conditions, and they were able to collect the first gas to evaporate. When they tested this in an atomic spectrometer, the heated gas gave off an extraordinary glow: Travers wrote, ‘the blaze of crimson light from the tube told its own story and was a sight to dwell upon and never forget’. (A simpler method of fractional distillation is now used to extract neon from air.)

The Neon Spectrum

Neon only gives off that one vivid red shade of light. So why do we think of neon lighting as being multicoloured? The answer is that, because neon came first, it gave its name to a style of light – other colours are produced using different gases, coloured glass, or fluorescent powders baked onto the inside of the glass tubes. For instance, helium or sodium produce an orange light, argon a lavender light, krypton a blueish white or yellowish green, and for blue you can use xenon or mercury vapour.

Ramsay’s thirteen-year-old son suggested calling the new gas ‘novum’ after the Latin for ‘new’: Ramsay adapted the idea, using the Greek-derived ‘neon’ instead. While it was a remarkable discovery, neon was initially a pretty boring element, since it is the least reactive of all: in fact, there are no elements that it will react with.

However, that brilliant red light fired up the imagination of the French chemist and inventor Georges Claude, who used an electric discharge in a closed glass tube containing neon to make an entirely new kind of light. His neon lamps were first displayed as a curiosity at a 1910 Paris exhibition. However, it took him over a decade to find a commercial use for the device (because people simply didn’t want red light in their homes or streets). Once he worked out a way to use bent tubes to make letters that glowed, his company Claude Neon found success, in America in particular. The first neon signs were sold to a Los Angeles car dealership, where passers-by would stop to gawk at this amazing newfangled piece of advertising.