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Creating the rules about discovery of elements


Deciding who discovered each element
Norman Greenwood Scientist
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Outside the university I was still interested in the affairs of IUPAC [International Union of Pure and Applied Chemistry], was very much still working in the atomic weights area, and because of that I was called on to be one of the two chemists on an international group that looked into a very important problem. The other member was Yves Jeannin from Paris. And the problem had to do again in the general area of atomic weights, but not so much the determination of atomic weights but who discovered particular atoms. Now, all the elements up to element about 100, even 101, had been discovered by this time and there wasn’t particular contention about who had made the discovery.

But then during the Cold War period, after the war and in the ‘60s and ‘70s and ‘80s, there became a rather acrimonious competition between the Soviet Union and the United States, and then subsequently with Germany, on who had first made a particular element and this was important for a variety of reasons. Firstly, of course, there was the national pride which is very important in having people discovering new elements. But also the people who were doing the work were doing experiments at enormous cost and the funding agencies wanted to know that the cost was being repaid, and one only has to think in present days of CERN and the problems of funding big multinational things that this is a problem.

Now, let me explain the nature of the problem. What is a discovery? How do you discover an element? In fact, in the context that we’re talking about, which is the trans-fermium elements beyond element 101, discovery is not a very good word. It is synthesis. You are making it. You are making something that doesn’t exist. You are not finding something that does exist. But the way that science is organised in different countries means that there are considerable difficulties in making decisions about who first made a particular element. For example, what are the criteria for a discovery? We said that it should be a published paper in a refereed journal. Saying something at a conference didn’t count because, a) you could think you’d said it or, b) you’d said something different or, thirdly, by the time you’d come to write it up you’d changed your mind and modified it to some extent which might be crucial. So, it had to be a published paper and the date of receipt was the important thing. There is the problem or one of the problems.

In the USSR, certainly at that time, the Academy of Science published all their work internally as non-refereed reports. They circulated amongst the academies and they were not sent for public presentation until review processes and so forth had been carried out and sometimes that could be 18 months. In America, on the other hand, Glenn Seaborg’s group in Berkeley, California could do an experiment today, write the experiment up if it was clear-cut and have it published within a couple of weeks. So the date of doing the experiments was important. Whether an experiment was repeatable was important. Whether people outside the lab could do it was important, and also, remember, that we are making a new element and characterising it by its decay patterns and so forth. It may decay into unknown isotopes of lighter elements which had yet not been synthesised or, one group might prepare one isotope of the element. Another group might prepare another. They would have different isotopes and different masses. Are they the same element? Another problem. Another technical problem: these new elements are all unstable, many of them exist for a millisecond. How do you characterise an element in that time? How do you know what a half-life is? Well, a half-life is the time at which half the sample decays, but you haven’t got half a sample. You’ve got one atom. Some of these experiments you would do millions of encounters of atoms by the bombarding processes that they do. One of them will form this atom which the computer can pick out and you’ve got it. You might wait a week to get another one. If you’ve got three you’re lucky, but is it the same element? Is it the same isotope? Because half-time... half-life is an average? How do you average one or two events? It’s... there are technical 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: IUPAC, Paris, Cold War, USSR, USA: Germany, CERN, USSR Academy of Sciences, Berkeley, California, Yves Jeannin, Glenn Seaborg

Duration: 6 minutes, 33 seconds

Date story recorded: May 2011

Date story went live: 25 November 2011