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An elementary history lesson
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There’s hafnium... The hunt for missing elements is a story of ego, errors and national pride, finds Andrea Sella
aged 27 during the first world war created one of science’s great might-have-been stories. In recent years, there have been many books about the elements, either encyclopedic surveys, or quirkier and more readable companions. Now we have a very different offering: A Tale of Seven Elements by Eric Scerri, one of the foremost authorities on the history of the periodic table. This is the remarkable story of “What makes the idea so the seven elements still “missing” remarkable? It was a way of organising elements in from the periodic table by the the absence of any theory” early 20th century and how they
Element 85 got its name, astatine, after many false “discoveries”
Theodore Gray/Visuals Unlimited/Corbis
A Tale of Seven Elements by Eric Scerri, Oxford University Press, $19.95
TO CHEMISTS, the periodic table is the cornerstone that supports so much of our discipline. But it also has much wider appeal, illustrated by the proliferation of amusing periodic tables of such things as vegetables, furniture or cyclists. And there are T-shirts with element symbols spelling words like Be Er and C Ho Co La Te. In the mind of the chemist, though, the periodic table is overlain with the heuristics we use daily to rationalise chemical behaviour. The brainchild of Dmitri Mendeleev is remarkable because it was conceived as an empirical tool, a way to organise elements according to their properties in the absence of any theory. The periodic table was built in 1869, 30 years before the discovery of the electron, 40 years before Ernest Rutherford discovered the atomic nucleus and 50 years before quantum mechanics showed the onion-like structure of the layers of electrons that orbit the nucleus. But it was British chemist Henry Moseley at the start of the 20th century who provided the crucial insight into why the elements were ordered according to the charge on the nucleus rather than by mass. In so doing, he put precise limits on how many elements remained undiscovered. That he was killed
were found. I knew the history of three of them: technetium, hafnium and rhenium. But I had always passed over the other four: francium, astatine, promethium and protactinium. Scerri has tremendous human stories to tell, but what emerges strongly is the struggle to sift real discoveries from claims and counterclaims, with overbearing egos, national pride, errors and misunderstandings all adding to the fun. Given that our scientific heroes always triumph in the end, we are blissfully unaware of how their forgotten contemporaries had alternative proposals and data to present. With hindsight, it is easy
to laugh at the elements now consigned to the scrapheap of science, like anglohelvetium, which would have taken astatine’s place, had its “discoverers” actually found the element 85 they were looking for. In the thick of the chase, confusion reigned. Scerri tells these stories well. He reminds us that not all of Mendeleev’s predictions were correct, and he highlights the important role that discovering elements plays in understanding both the quantum theory of electrons and the nucleus. The crucial work of physicist Lise Meitner in the discovery of protactinium while her research partner Otto Hahn was fighting in the first world war is also brought to life wonderfully through their letters. Yet Scerri is not a natural popular science writer – his language seldom soars beyond the descriptive. The cut and thrust of the debate is meticulously footnoted, but we do not have a sense of who the people were and their motivations. There are also surprising omissions. For example, Scerri does not discuss the 2009 North American shortage of technetium, which is used in millions of medical diagnostic procedures each year. The element’s main source, the Canadian reactor at Chalk river, remained closed for much longer than expected after a leak. Availability of radioisotopes is still a serious issue. Yet despite the quibbles, this is a brilliant book about the interface of chemistry and physics. Above all, the stories argue powerfully for curiositydriven research, and show how hard it is to see the wood for the trees in the thick of a scientific battle. They are powerful reminders, too, that the scientific method always allows the truth to shine through, you just have to be patient. n Andrea Sella is a chemist at University College London 10 August 2013 | NewScientist | 51
There’s hafnium... The hunt for missing elements is a story of ego, errors and national pride, finds Andrea Sella
aged 27 during the first world war created one of science’s great might-have-been stories. In recent years, there have been many books about the elements, either encyclopedic surveys, or quirkier and more readable companions. Now we have a very different offering: A Tale of Seven Elements by Eric Scerri, one of the foremost authorities on the history of the periodic table. This is the remarkable story of “What makes the idea so the seven elements still “missing” remarkable? It was a way of organising elements in from the periodic table by the the absence of any theory” early 20th century and how they
Element 85 got its name, astatine, after many false “discoveries”
Theodore Gray/Visuals Unlimited/Corbis
A Tale of Seven Elements by Eric Scerri, Oxford University Press, $19.95
TO CHEMISTS, the periodic table is the cornerstone that supports so much of our discipline. But it also has much wider appeal, illustrated by the proliferation of amusing periodic tables of such things as vegetables, furniture or cyclists. And there are T-shirts with element symbols spelling words like Be Er and C Ho Co La Te. In the mind of the chemist, though, the periodic table is overlain with the heuristics we use daily to rationalise chemical behaviour. The brainchild of Dmitri Mendeleev is remarkable because it was conceived as an empirical tool, a way to organise elements according to their properties in the absence of any theory. The periodic table was built in 1869, 30 years before the discovery of the electron, 40 years before Ernest Rutherford discovered the atomic nucleus and 50 years before quantum mechanics showed the onion-like structure of the layers of electrons that orbit the nucleus. But it was British chemist Henry Moseley at the start of the 20th century who provided the crucial insight into why the elements were ordered according to the charge on the nucleus rather than by mass. In so doing, he put precise limits on how many elements remained undiscovered. That he was killed
were found. I knew the history of three of them: technetium, hafnium and rhenium. But I had always passed over the other four: francium, astatine, promethium and protactinium. Scerri has tremendous human stories to tell, but what emerges strongly is the struggle to sift real discoveries from claims and counterclaims, with overbearing egos, national pride, errors and misunderstandings all adding to the fun. Given that our scientific heroes always triumph in the end, we are blissfully unaware of how their forgotten contemporaries had alternative proposals and data to present. With hindsight, it is easy
to laugh at the elements now consigned to the scrapheap of science, like anglohelvetium, which would have taken astatine’s place, had its “discoverers” actually found the element 85 they were looking for. In the thick of the chase, confusion reigned. Scerri tells these stories well. He reminds us that not all of Mendeleev’s predictions were correct, and he highlights the important role that discovering elements plays in understanding both the quantum theory of electrons and the nucleus. The crucial work of physicist Lise Meitner in the discovery of protactinium while her research partner Otto Hahn was fighting in the first world war is also brought to life wonderfully through their letters. Yet Scerri is not a natural popular science writer – his language seldom soars beyond the descriptive. The cut and thrust of the debate is meticulously footnoted, but we do not have a sense of who the people were and their motivations. There are also surprising omissions. For example, Scerri does not discuss the 2009 North American shortage of technetium, which is used in millions of medical diagnostic procedures each year. The element’s main source, the Canadian reactor at Chalk river, remained closed for much longer than expected after a leak. Availability of radioisotopes is still a serious issue. Yet despite the quibbles, this is a brilliant book about the interface of chemistry and physics. Above all, the stories argue powerfully for curiositydriven research, and show how hard it is to see the wood for the trees in the thick of a scientific battle. They are powerful reminders, too, that the scientific method always allows the truth to shine through, you just have to be patient. n Andrea Sella is a chemist at University College London 10 August 2013 | NewScientist | 51