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Week forty-five: ASTATINE (probability 1361), by David Sutton

ASTATINE is a chemical element, no. 85 in the Periodic Table. It is the rarest of all the naturally occurring elements: it is thought that any one time there is no more than one ounce of astatine on earth, making its nearest contender in the rarity stakes, FRANCIUM, look relatively abundant at twenty ounces or so.

Here's a little test: write down as many names of chemical elements as you can (there are 118 in all). If you manage more than about sixty, I suspect that you are either a professional chemist or very good at memorising the words of Tom Lehrer songs. I have been brushing up my own knowledge by reading Sam Kean's 'The Disappearing Spoon', a book crammed with fascinating lore about the elements along with anecdotes about their sometimes eccentric discoverers. Here are a few notes on shorter names that may be less familiar to you.

THULIUM is element 69, a rare earth or lanthanide. It is impossible to obtain completely pure THULIUM, it is always contaminated by other rare earth elements.

CERIUM, element 58, is another lanthanide. It sparks when struck, making it ideal for use as flints in cigarette lighters. It kept the Jewish writer Primo Levi alive when he was working in a prison chemical plant during the holocaust — he would appropriate small sticks of cerium and barter them with civilians for bread and soup.

THALLIUM, element 81, is considered the deadliest element in the table. It replaces potassium in the body, causing massive damage. The CIA are alleged to have plotted to assassinate Fidel Castro by powdering his socks with thallium-tainted talcum powder.

RHODIUM, element 45, is the most expensive of all the elements that can actually be bought commercially. It is strange to think that at one time this prestigious position was held by the now ubiquitous ALUMINIUM (or ALUMINUM), until someone figured out how to separate it from oxygen.

HAFNIUM, element 72, was not nailed down till 1922 when Niels Bohr, applying reasoning based on the principles of the new quantum physics, decided that the best place to look for it was in samples of ZIRCONIUM, and despatched two chemists to do that. They found it first time.

It is worth noting that many elements went through several names or proposed names before settling down to their present identities. ASTATINE, for example, was first proposed as ALABAMINE, after Alabama where it was first found; another early name for it was HELVETIUM. VIRGINIUM was proposed for FRANCIUM. PROMETHEUM was once called ILLINIUM. JOLIOTIUM+, not currently valid but about to make an appearance in CSW12, is a former name for DUBNIUM. SILICON was originally called SILICIUM. TUNGSTEN has an alternative name WOLFRAM, and even TIN can be called STANNUM.

And let us not forget DIDYMIUM, NEBULIUM and CORONIUM, three elements that never were, being discoveries that turned out to resolve into existing elements. Some you win, some you lose...

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