Chemistry in its element: element 118
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This week the chemist's that are seeking fame. Here's Andrea Sella.
We live in an age when everyone is just gagging to be 'famous'. Andy Warhol, of course, pointed out that everyone was likely to be famous for 15 minutes. But the real question is, if you're a chemist, or a scientist generally, what does it take to become famous? How do earn the adulation of the masses? And if not the masses, at least of your peers?
You'd think a Nobel prize would do it. But you'd be surprised how few of them anyone can actually remember, apart from a few early 20th
century heroes. And to have an element named after you need to be dead. So that seems quite pointless.
What if you discovered a new element? For about 70 years, ever since plutonium slipped out of a nuclear reaction, the search has been on to make ever heavier and more exotic elements to add to our periodic table. And I emphasise the word 'make' because it is no longer a question of finding a rock and extracting from it some mysterious substance that does not fit the description of anything that has come before. No, you actually have to make it from scratch.
So how do you make an element? Well new atoms of, admittedly old, elements, are being made all the time. Nuclear fusion of hydrogen is the fundamental process that powers stars. But as stars age and steadily run out of hydrogen they gradually start fusing heavier nuclei and it is then possible to make ever heavier atoms. It's brutally difficult because you have to get past the huge positive charges of the two nuclei to get them to fuse. Stars can do this nucleosynthesis up to iron. Unfortunately that's where things end.
After that the way to make anything heavier is by adding neutrons. Because the neutron has no charge it can sneak quietly into the nucleus. The neutron can then add to the total mass count, and the nucleus can then decay by spitting out an electron to give you something that is one place higher along in the periodic table. And repeating this process laboriously - one step forward, one step back - will take you all the way out towards uranium, which at atomic number 92 is about as high as one can find lying around in universe.
But can one go beyond? The answer turns out to be yes. Teams in the US, Germany, Japan and Russia have been hard at work doing it. And the process is incredibly difficult. Essentially what they do is strip atoms down to their nuclei and then accelerate them to phenomenal speeds using a particle accelerator, and then slam these ions into a target. So for example the element lawrencium was made by bashing a californium target with naked boron nuclei.
This is not work for the lone experimenter working in a shed somewhere. These are experiments of extraordinary subtlety and complexity. And the problem is not just making the new element but also figuring out what you've got at the end. The problem is that you only make a few atoms at a time and these products tend to be spectacularly unstable so you sometimes have only a few milliseconds in which to work out what you've got. It's complex. It's expensive. And very, very clever. And each new atom really is a whole new chemical world to explore. Can it be any wonder that it attracts fortune seekers?
In June 1999 the Lawrence Berkeley Lab in California, one of the few places in the world that does this sort of work announced in the journal
Physical Review Letters
that they had succeeded in making ununhexium and ununoctium, which in plain English means elements 116 and 118, by bashing a lead target with krypton nuclei. Huge excitement followed because these were by far the heaviest elements ever made. It seemed a real breakthrough. The method they had used was also a departure from previous work - a new strategy that had gone spectacularly well. The secretary of energy, whose department had funded the work noted that four of the senior members of the team were foreign said 'this stunning discovery which opens the door to further insights into the structure of the atomic nucleus also underscores the value of foreign visitors and what the country would lose if there were a moratorium on foreign visitors at our national labs. Scientific excellence doesn't recognise national boundaries, and we will damage our ability to perform world-class science if we cut off our laboratories from the rest of the world.'
The problem was however, that no one else could repeat the work. Labs in Germany and Russia reported that they got different results. A major process of soul-searching started in California and the data began to be picked over in great detail. A painful investigation concluded that one of the team leaders Victor Ninov, a Bulgarian national, had fabricated the crucial data. Confronted with the evidence, Ninov denied everything. But in Germany, irregularities came to light in the data associated with an earlier discovery he had been involved with - that of elements 111 and 112. Ninov was fired. The Berkeley led group were then forced to do the unthinkable - to publish a retraction, the author list being one name shorter than the original paper. It was the scientific equivalent of hara kiri.
But did element 116 really not exist? In 2000, the rival group in Russia reported having made a single atom of element 116 and within 3 years had succeeded in making more atoms of two different isotopes of this element. 118, on the other hand, had to wait until 2002 for successful synthesis by a route that differed from that used by the Americans. So 116 and 118 are real, and their properties are slowly being mapped out even as we speak. But does anyone remember the names of the people who are the rightful discoverers? Does the name Oganessian ring a bell? Probably not.
It's more likely that you remember the name of Victor Ninov, the man at the centre of the storm. Perverse, isn't it? But it's the way of the world. Fame, even in science, is a fickle mistress.
Perhaps the net aim then, rather than finding an element could be to find a way to preserve these legacies. Just a thought. That was University College London's Andrea Sella with the fundamental not famous chemistry of elements 116 and 118. Now next week a two faced element.
Sodium, like most elements in the periodic table could be said to have a dual personality. On one side it is an essential nutrient for most living things, and yet, due to its reactive nature is also capable of wreaking havoc if you happen to combine it with something you shouldn't.
As such sodium is found naturally only in compounds and never as the free element. Even so it is highly abundant, accounting for around 2.6 per cent of the earths crust by weight.
And to find out some of the beneficial, as well as lethal roles of sodium - as well as the mystery behind it being given the symbol Na, join David Read from the University of Southampton in next week's Chemistry in its element.
Chemistry in its element is brought to you by the Royal Society of Chemistry and produced by
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