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Neon

April 22, 2012

I’ve decided I don’t really like neon. All mouth and no trousers as my mum would say.

A Neon Sign

Neon has one, attention-grabbing party trick and the rest of time its just doing a very bad impression of helium. Even the name neon is dull. Many of the elements in the periodic table are named after their place of birth, or an eminent scientist, or the name describes the element’s character. Neon was named not by its discoverer Sir William Ramsey but by his young son. William Ramsey junior suggested ‘novum’ for new which was amended to neon because of the convention of naming elements in Greek rather than latin. And that is it. No searching around for a name to inspire or illuminate us, just ‘new’.

So what does neon do? Well, not much. It doesn’t react with anything to form any compounds – just like helium but helium didn’t do anything first and stole all the non-glory for itself. It is lighter than air so it will just about float a balloon but not as well as helium. It forms a liquid at -246 degrees Celsius – just between the boiling points of helium and nitrogen but is considerably more expensive and doesn’t do any of the interesting creeping tricks like helium. The expense is due to neon’s rarity on Earth (only one part in every 65,000 by volume in our atmosphere) despite being relatively abundant in the rest of the universe. One slightly exciting application is in helium/neon lasers (affectionately known as HeNe) but even these are run-of-the-mill lasers that no self respecting Bond Villain would look at twice.

So that party trick had better be good. It is of course neon’s use in, wait for it … neon signs! When you pass an electric current through a tube of neon is glows a bright red/orange colour. But guess what! Helium does it too and makes a rather attractive pink colour. In fact all the noble gases glow in this way producing a range of colours. Neon was the gas most commonly used for this type of lighting and has donated its name to all noble gas lights even when neon isn’t involved. Once neon signs were the perfect answer to advertising. The tubes of gas could be moulded into any number of different shapes and the bright light could be seen at a great distance. To some these lights were a sign of modernity but to others the red colour suggested something more seedy and disreputable.  Today very few of these lights are used and what might look like a neon sign is often LED lighting.

But wait! Neon has one last very cool trick up its sleeve. The only problem is that you have to travel to Jupiter to see it. Satellite observations of Jupiter discovered that the outer atmosphere of the planet contained a lot less helium and neon than expected, about 90% less. The missing gas was soon found but much but deeper down. Drawn in by gravity towards the centre of the planet the gas comes under intense pressure and, around the liquid metallic hydrogen layer at about a quarter of the way to the centre, it condenses into a liquid. The liquid droplets experience fiction as they fall and if the drops are big enough and if there is enough friction the droplets will glow in the same way as a neon sign. Imagine streaks of brilliant crimson like millions of tiny meteorites against the backdrop of an orange red Jupiter sky – neon rain.

Maybe neon isn’t so boring after all.

Next time we shuffle and groan our way through zombies and salt, its sodium!

@RotwangsRobot

Image @TravisHawke and @SciCommStudios

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