Einsteinium

Meera Senthilingam 

This week, there's no need to even guess who this element is named after, but it's more than fame that got this element its name – Brian Clegg 

Brian Clegg 

At first glance there's nothing odd about naming element 99 in the periodic table 'einsteinium'. After all, Einstein is the most famous scientist that has ever lived. Yet fame is not usually a good enough reason to make it into the exclusive club of the elements. Although the likes of Lawrence, Rutherford, Seaborg and Bohr have been honoured, there's no Newton or Laplace, Dalton or Feynman. Not even the new saint of science, Darwin. 

The clue to Einstein's position here is that many of those with elements named after them played a fundamental role in our understanding of atomic structure. There is the odd highly doubtful case –  but Einstein isn't one of them. He's not on the table because he's famous, but because he was responsible not only for relativity but for laying some of the foundations of quantum theory, which would explain how atoms interact. What's more, his study of Brownian motion was the first work to give serious weight to the idea that atoms existed at all. 

For such a great figure, einsteinium verges on being an also-ran. It's one of the actinides, the second of the floating rows of the periodic table that are numerically squeezed between radium and lawrencium. Although only tiny amounts of it have ever been made, it's enough to determine that like its near neighbours in the table it is a silvery metal. Around twenty isotopes have been produced with half-lives – that's the time it takes half of the substance to decay - ranging from seconds to over a year, though the most common isotope, einsteinium 253 only has a 20 day half life. 

Apart from its name, what makes einsteinium stand out is the way it was first produced. When the Soviet Union developed its own atomic bomb, America felt it had to have something even more powerful to keep ahead. Using an atomic bomb as a trigger, the new type of device, referred to as a 'Super' would apply so much heat and pressure to the hydrogen isotope deuterium that the atoms would fuse together, just as they do in the Sun. It was to be the first thermonuclear weapon. The H bomb.

After months of technical testing of components, the first thermonuclear bomb was ready to be tried out at a remote island location, Elugelab on the Eniwetok Atoll in the South Pacific. Like the innocently named Little Boy and Fat Man – the bombs that were dropped on Hiroshima and Nagasaki – this bomb had a nickname. It was called 'the sausage' because of its long cylindrical shape. 

When the bomb exploded on November the first, 1952, it produced an explosion with the power of over 10 million tonnes of TNT – five hundred times the destructive power of the Nagasaki explosion, totally destroying the tiny island. This was very much a test device – weighing over 80 tons and requiring a structure around 50 feet high to support it, meaning that it could never have been deployed – but it proved, all too well, the capability of the thermonuclear weapon. And in the moments of that intense explosion it produced a brand new element. 

As part of the aftermath of the test, tonnes of material from the fallout zone were sent to Berkeley, the home of created elements, for testing. There among the ash and charred remains of coral were found a couple of hundred atoms of element 99, later to be called einsteinium. Such was the secrecy surrounding the test, the element's discovery was not made public for three years. It was in Physical Review of August the first 1955 that the discoverer Albert Ghiorso and his colleagues first suggested the name einsteinium. 

In the intense heat and pressure of the explosion, some of the uranium in the fission bomb that was used to trigger the thermonuclear inferno had been bombarded with vast numbers of neutrons, producing a scattering of heavier atoms. At the same time, neutrons in the newly formed atoms' nuclei underwent beta decay, producing an electron and a proton. So instead of just getting heavier and heavier uranium isotopes, the result was an alchemist's delight of transmutation, ending up with einsteinium 253. 

Not surprisingly, this production method is not the norm. Now, when einsteinium is required, plutonium is bombarded with neutrons in a reactor for several years until it is has taken on enough extra neutrons in the nucleus to pump it up to einsteinium. This only produces tiny amounts - in fact after its discovery it took a good 9 years before enough einsteinium had been produced to be able to see it. 

In part the tiny quantities of einsteinium that have been made reflect the difficulty of producing it. But it also receives the sad accolade of having no known uses. There really isn't any reason for making einsteinium, except as a waypoint on the route to producing something else. It's an element without a role in life. 

We started by thinking of why Einstein might be honoured by appearing in the periodic table. It's true that Albert Einstein made a huge contribution to the understanding of atoms and atomic structure. But it's hard not to see his presence in einsteinium being more because of the application of his iconic equation E=mc² that he hated. The conversion of mass to energy in the world's most destructive weapons. 

If Einstein can be considered the father of the nuclear explosion, then einsteinium will always be the child of the bomb. 

Meera Senthilingam 

That's quite a birth to come from an atomic bomb. That was Brian Clegg with the explosive origins of einsteinium. Now next week we've got a very useful element with many roles in life, including multiple ways of protecting our health. 

Simon Cotton 

It is also used in sunscreens, since it is a very opaque white and also very good at absorbing UV light. When UV light falls upon it, it generates free electrons that react with molecules on the surface, forming very reactive organic free radicals. Now you don't want these radicals on your skin, so the TiO2 used in sunscreens is coated with a protective layer of silica or alumina. In other situations, these radicals can be a good thing, as they can kill bacteria. You can put very thin coatings of TiO2 onto glass (or other substances like tiles); these are being tested in hospitals, as a way of reducing infections. 

Meera Senthilingam 

And Simon Cotton will be bringing us more of the uses and properties of titanium in next week's Chemistry in its Element. Until then, I'm Meera Senthilingam and thank you for listening.