Thinking, Periodically

This item first appeared in 2008

Professor John Nicholson on the periodic table of the elements

The Great Achievement of Chemistry. That’s how Professor John Nicholson summed up the periodic table of the elements as he rounded off his talk to a fascinated audience at the University of Bristol. Appropriately for the year marking the centenary of the death of Mendeleev, Professor Nicholson started off the Bristol and South-West Regional Group lecture programme for 2007/08 by presenting his ‘Random Walk Around the Periodic Table’, treating all listening to a potted history of elemental classification, peppered with enlightening yet obscure scientific and historical facts. Starting from the ‘classical’ era, advancing through the alchemical age and eventually arriving at what we know as modern chemistry, Prof. Nicholson ably guided those present through the trials faced by scientists in their struggles to classify the elements. Beginning by focussing upon the initially-scorned work of J.A.R. Newlands and his controversial ‘Law of Octaves’, though to the ground-breaking work of Mendeleev and his discovery of the ‘periodic law’, of which the periodic table we all know today was the natural extension.

Along the way, we were told of the problems both Newlands and Mendeleev faced, such as the historical problems presented by the similarities of Iodine and Telurium, and where to place a troublesome element such as Uranium. Also recognised was the eminent physicist Henry Moseley, whose ground-breaking work showed that atomic number was not an arbitrary value, and further proved that predictions about the elements could be made with good degrees of certainty. Along the way, Professor Nicholson accompanied his tale with fascinating pictures – a photo of the chemistry laboratory of Bristol’s Clifton College from 1898, complete with the then-accepted version of the periodic table hanging on the wall, was a particular highlight with the local audience.

As well as this whirlwind tour of chemical history, the audience were given frequent nuggets of information about specific elements, showcasing the varied properties across the table, and the fascinating tales of isolation and discovery associated with the elements within. Iron, for example, was highlighted for its huge impact upon western civilisation – lending itself to a whole historical epoch, the central role it played for engineering and the industrial revolution, all the way through to the discovery of ferrocene and the resulting ‘renaissance’ of inorganic chemistry that followed. The ‘capital experiment’ of Humphrey Davy in the isolation of potassium from electrolysis of fused potash, and curious metalloid properties of antimony were highlighted, but few tales raised as many smiles as that of Hennig Brande and the discovery of phosphorous – the lone scientist desperately trying to isolate gold, convinced that the yellow tinge of urine betrayed the presence of the metal, and thus reducing bucket after bucket down as he chased the absent metal, but managing nevertheless to isolate a new, phosphorescent element nonetheless!

As is inevitably the way with such a wide-ranging, amusing and beguiling subject, it felt as those there was not enough time to cover all the tales that could have been relayed, but Professor Nicholson got the new lecture programme off to a wonderful start, as was clearly seen by the enthusiastic question and answer session afterwards, which was doubtless continued by some of the attendees while eating after the talk with the speaker.

The group will next be recognising the achievements of undergraduate chemistry and chemical engineering students at the universities of Bath and Bristol, before returning to another invited speaker to further the lecture programme. See the Regional Group schedules for further information if you would like to attend any of the lectures.

Derek Gillespie
Bristol and South-West Region Honorary Recorder

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