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The nature of discovery: a supernova


Creating the rules about discovery of elements
Norman Greenwood Scientist
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We had a group which was formed under the chairmanship of Sir Denys Wilkinson, who is a distinguished physics professor originally from Cambridge then to Oxford and then Vice- Chancellor at the University of Sussex in Brighton, or near Brighton. And there were about five or six other physicists as members plus two chemists, myself and Yves Jeannin. This was a joint IUPAP [International Union of Pure and Applied Physics] physics and IUPAC [International Union of Pure and Applied Chemistry] chemistry committee, and we had to agree first of all on the criteria and that took a long while. Then we had to visit each of the labs which were major players in this, principally Berkeley, GSI in Darmstadt and Dubna in... north of Moscow... to find out what they were doing and what they agreed.

Now, to give you some idea of the difficulties this was not the first committee that had been formed. The first committee had been formed I think a decade earlier under the chairmanship of Jack Lewis, and Jack Lewis is no mean person when it comes to running committees. He had a committee. I don’t think they actually ever met once. They may have corresponded but not everyone did. It really just was in the long grass and nothing happened. So we had a difficult job, but Denys Wilkinson was very patient, took his time. We thought at first he was taking too long but in retrospect he knew exactly what he was up against and he was a superb nuclear physicist as well, and we visited Berkeley for nearly a week and then Dubna. Well, actually the order of it doesn’t matter but we visited in turn Berkeley, GSI in Darmstadt and Dubna and looked at their experiments and tried to judge as fairly as we could the discovery process or the first formations and this took quite some time – two or three years to do – but we finally had a consensus which we put to the laboratories of main concern and they were able to comment on this and then it was published both in physics and chemistry journals and those judgements, I think it’s fair to say, have stood the test of time.

The criteria are still exactly the criteria that are used 20 years later now and the assessment of the particular elements was now accepted, albeit grudgingly in some cases. Sometimes we said the judgement should be joint. It should be a joint credit given. Sometimes it was one laboratory, sometimes another one and there was just one other problem that sometimes an observation is made and it is recorded but people don’t know what it is and then someone else does an experiment which immediately makes you say, ah the original experiment meant something, a new element. Which is the discovery, the second one or the first one, or both together? It’s not a simple field but I think that was a very important job and it was important for one, final, further reason. Because national pride, and indeed personal pride and ego, was involved in this – understandably – people wanted the right to name an element.

Now, at this stage, and I’m talking 1990, 1991, the person or the group that was charged with the naming of the elements was the International Union of Pure and Applied Chemistry, and they would consult both the Atomic Weights Commission of which I’d been chairman and the Nomenclature Committee for obvious reasons because, interestingly enough, you can’t just name an element whatever you want. Sometimes it doesn’t translate. Sometimes it’s almost a swear word in some other languages. Other times it is misleading, and so you have to have an agreement on the name. But the person who’s discovered it said, hey this is my element I discovered it, and so again there’s a problem.


That was not our problem. We had the criteria of discovery which we solved. Since then all the elements which have subsequently been discovered – and we’re up to about 118 now – most of the elements have been discovered though not all, between 101 and 118... interestingly enough, one of the important facts coming from this is that the so called island of stability, the theoretical concept that whereas heavier and heavier elements get more and more unstable what is happening is that as you go to even further... you come to what are called ‘magic number nuclei’ and they should become more stable, and that was predicted by the theoretical physicists and there seems to be growing evidence now that the half-life of some of these new isotopes which are being made of the heaviest elements are, in fact, rather longer than the ones immediately after 101.

So those elements are now being named and the problem is, of course, a continuing one because the work is continuing, but it was a very interesting example of international collaboration at its best where goodwill finally came and, of course, in a sense the Cold War aspect has disappeared now because that era of politics has passed. But the chemistry is still advancing and still there are the personal and laboratory problems.

Norman Greenwood (1925-2012) was born in Australia and graduated from Melbourne University before going to Cambridge. His wide-ranging research in inorganic and structural chemistry made major advances in the chemistry of boron hydrides and other main-group element compounds. He also pioneered the application of Mössbauer spectroscopy to problems in chemistry. He was a prolific writer and inspirational lecturer on chemical and educational themes, and held numerous visiting professorships throughout the world.

Listeners: Brian Johnson

Professor Brian FG Johnson FRS, FRSE, FRS Chem, FAcad Eu, FAS. Professor of Inorganic Chemistry University of Edinburgh 1991-1995, Professor of Inorganic Chemistry University of Cambridge 1995-2005, Master Fitzwilliam College Cambridge 1999-2005. Research interests include studies of transition metal carbonyls, organometallic chemistry, nano- particles and homogeneous catalysis. Professor Johnson is the author of over 1000 research articles and papers.

Tags: Cambridge University, Oxford University, University of Sussex, Brighton, IUPAP, IUPAC, Berkeley, GSI Helmholtz Centre for Heavy Ion Research, GSI, Darmstadt, Dubna, Atomic Weights Commission, Nomenclature Committee, Cold War, Denys Wilkinson, Yves Jeannin, Jack Lewis

Duration: 6 minutes, 50 seconds

Date story recorded: May 2011

Date story went live: 25 November 2011