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Boron

February 18, 2012

Boron is like the shy kid who is quietly good at most subjects in school.  Unlike most of the other elements Boron is not born in stars but was first created in the Big Bang and continues to be made by cosmic rays  in deep space or the upper reaches of Earth’s atmosphere. Despite its relatively low abundance and low profile boron has found its way in to many aspects of our everyday life and for many of us we don’t even notice.

Boron’s quiet brilliance and versatility all stems from its being three electrons away form the ‘ideal’ helium structure. Giving away three electrons is a big ask, especially when that only leaves you with two, so boron likes to share. Boron will share each of its three outer electrons in exchange for a share of an electron from three other atoms (totalling six). Admittedly some elements are very selfish and tend to the hog the electrons offered by boron but others are more generous. Boron will even shuffle everything round to accommodate two electrons from one donor atom to make up a full, happy, complete shell or octet. See supplementary post on atomic structure for a better explanation (due later this week).

Boron’s uses include: Pyrex (or borosilicate) cookware in your kitchen as it is more resistant to thermal shock than conventional glass; neodymium magnets (and you thought they just contained neodymium); insecticides (in the form of boric acid); bullet proof vests (in the form of boron carbide) and to keep swimming pools clean (again in the form of boric acid).

There is a good chance that boron is also sitting in your washing powder, in the form of sodium perborate, ready to do its bit oxidising, and thereby bleaching, stains on your washing. You may also have seen boxes of borax in pharmacies allegedly for use in laundry but I suspect most of these are now sold to teachers and parents wanting to do ‘goo‘ demonstrations with their kids.

Boron also forms compounds with hydrogen called Boranes which, similarly to their carbon equivalents, burn to release a huge amount of energy. The story I was told as an undergraduate went something like this. During the height of the cold war an American spy managed to sneak in to a rocket testing facility in Russia. Whilst there he observed a test launch and to his surprise saw green flames billowing out of the rocket’s thrusters. He quickly sent a message back to America describing his observations and American scientists deduced that the Russians were experimenting with borane fuels. These highly reactive compounds were known to be very effective rocket fuels but were difficult to handle and toxic. The Americans had carried out relatively little research up to then, and loathed to be left behind by the Russians, they began pouring money into researching borane technology.

It later emerged that the spy was colour blind and that the flames he had observed were orange all along. The use of boranes as fuel for rockets and aircraft, like the Lockheed SR-71 ‘Blackbird’, seems to have ended. However, boron still occasionally makes a star turn in pyrotechnics such as flares and fireworks – just look for the characteristic green flames.

Brace yourself for greatness. Next week its carbon.

@RotwangsRobot

Images by @SciCommStudios

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