Periodic Tales

by Hugh Aldersey-Williams

  Seaborg was excited by the new realm on the border of physics and chemistry where chemical elements could be transformed into one another and to which these powerful laboratories held the key. As soon as he could, he was doing his own radiation experiments. While still a graduate student at the University of California at Berkeley, for example, he bombarded tellurium with deuterium atoms and neutrons in order to convert it into a heavy isotope of iodine whose radioactive presence could be traced and used to monitor the functioning of the thyroid gland. Tumours could then be found by using a Geiger counter to locate the hotspots where the iodine concentrated. Working with tellurium is always unpleasant–the compound that it forms with hydrogen is like hydrogen sulphide, with its infamous rotten-eggs smell, but far more offensive. Later, Seaborg managed to delegate the tellurium chemistry to his own student, who had great trouble ridding himself of the stink. Days afterwards, it was even possible to tell which library books he had been consulting from the revolting odour they exuded.

  Seaborg was not content to leave his experiments in transmutation of the elements at that. He realized that the apparent ceiling on the number of the elements was only a matter of power. The strong nuclear force that binds neutrons and protons together to form the nuclei of atoms is only strong over extremely short distances. In larger atomic nuclei, the mutual repulsion of the positive electric charges of the protons becomes more important. ‘At some point, the two forces could equalize. No one had realized that this might be why we had found no elements in nature with more protons than uranium’s 92,’ Seaborg wrote in a memoir.

  The obvious thing then was to bombard uranium with particles and see whether any of them stuck. By early 1939 there were other reasons to do this. The world was arming rapidly in preparation for global war. Atomic fission had been reported by Otto Hahn in Nazi Berlin. Hahn had bombarded uranium atoms with neutrons and found not merely small particles breaking off as in a natural radioactive decay chain but whole atoms splitting in two–he was baffled to find barium, just over half the atomic mass of uranium, among his reaction products. His bafflement subsided somewhat when his long-time collaborator, the Jewish Lise Meitner (with whom he had discovered the element protactinium in 1918, and who was now in exile in Sweden), made calculations that confirmed the truth of what he had seen but not believed. She also noticed that heavy uranium, whose atoms contained more than the usual number of neutrons, could be expected to split into atoms of less massive elements with the release of huge amounts of energy. Seaborg’s colleague Ed McMillan soon made similar observations, which led him to the conclusion that not all the uranium atoms split in this way, and that some might simply be absorbing the neutrons. If so, they would be transmuted into atoms of a new element, number ninety-three. This supposition was soon confirmed and the discovery published in 1940. By this time, Europe was at war, and the open publication of such potentially strategic information provoked a furious reaction from the British. It seems that the only thing that was kept quiet was the element’s name: McMillan had chosen to call it neptunium, following the precedent of uranium, even though the planet Neptune had by then been known for nearly a century, but this information was not made public until after the war.

  Seaborg’s research into element number ninety-four was to proceed by contrast under a cloak of secrecy. Neptunium had too short a half-life for many applications, and certainly for making what was now being referred to as an ‘atomic bomb’ (although H. G. Wells seems to have coined the phrase in his 1913 novel The World Set Free). But there was reason to think the next element in the sequence would be different. The research began at Berkeley, but following the American entry into the war and the setting up of the Manhattan Project, the locus of the effort to synthesize plutonium moved to Chicago. Seaborg worked here for three years until 1945 in a building called, with deliberate obfuscation, the Metallurgical Laboratory, or Met Lab. The first task was to build an atomic pile in which slugs of uranium were stacked in such a way that they would undergo a chain reaction to produce element number ninety-four. At the start, the sought-for element was referred to simply as 94, but, as this was a little obvious, the chemists brightly adopted the code number 49 instead and took to calling it ‘copper’. This was fine until one experiment actually required some copper, which then had to be distinguished by calling it ‘honest-to-God copper’.

  The new element was isolated in August 1942. Seaborg wrote–rather self-consciously–in his journal about ‘the most thrilling day’ in the Met Lab: ‘Our microchemists isolated pure element 94 for the first time! It is the first time that element 94 (or any synthetic element, for that matter) has been beheld by the eye of man. I’m sure my feelings were akin to those of a new father who has been engrossed in the development of his offspring since conception.’

  Next, the offspring had to have a proper name. Extremium and ultimium were rejected, wisely in view of the chemical and military events that were to unfold. Seaborg instead followed McMillan’s example and took advantage of the fact that there was one planet in the solar system left for inspiration, Pluto, which had been discovered in 1930. ‘We briefly considered plutium, but plutonium seemed more euphonious,’ he wrote later, insisting that the planets had been his only guide in choosing a suitable name. When he was reminded that Pluto is also the Roman god of the underworld and of the dead, Seaborg insisted that any such symbolic meaning was ‘entirely coincidental; I was unfamiliar with the god or why the planet was named for him. We were simply following the planetary precedent.’

  I think the chemist protests too much. Seaborg had literary leanings at school and came relatively late to science. It seems impossible he could have been unaware of Pluto’s darker meanings. Certainly, his thinking was more knowing when it came to the chemical symbol. ‘Each element has a one-or two-letter abbreviation. Following the standard rules, this symbol should be Pl, but we chose Pu instead,’ he explained. P.U.–peee-euggh –was and is American slang for a stink, something objectionable. ‘We thought our little joke might come under criticism, but it was hardly noticed.’ For certain key workers on the chemical side of the Manhattan Project, there was even ‘the UPPU club’–you pee plutonium. To qualify for membership you had to have had enough exposure to plutonium for it to show up in your urine.

  Seaborg had his first microscopic speck of plutonium by August 1943, a year after he had isolated the first invisible atoms. Another year later, his reactors were producing masses of a gramme or more, which were stockpiled at Los Alamos. With the need to press on and complete the building of the bomb, there was little time for meditation on the thrill of discovery, and still less for much consideration of what plutonium was actually like. In most cases, the discovery of an element is followed by a rush of chemists keen to measure its properties, test its reactivity and prepare its compounds. In the case of plutonium, it was important to verify certain highly technical parameters to do with its nuclear decay. But beyond that, nobody seemed to care. Even the name–the usual sign of pride in what one has brought into the world–had to wait before the world could know it. At the end of the war, some of the Manhattan Project workers and their wives got together for a game of charades, which confirmed that secrecy had been maintained: ‘When the husbands tried to act out the word “plutonium,” the wives were mystified; they’d never heard of the stuff.’

  The natural chemist in Seaborg reappeared much later. In a 1967 report called with perhaps unintentional poetry The First Weighing of Plutonium, he described his new chemical element with obvious awe: ‘Plutonium is so unusual as to approach the unbelievable. Under some conditions it can be nearly as hard and brittle as glass; under others, as soft as plastic or lead. It will burn and crumble quickly to powder when heated in air, or slowly disintegrate when kept at room temperature…And it is fiendishly toxic, even in small amounts.’ Despite all this, Seaborg fondly believed that plutonium might one day replace gold as a monetary standard. Maybe he really was oblivious of all plutonian symbolism.

&nb
sp; The potency of plutonium was–and still is–felt in another sphere, of course. A few pounds of the element is enough for an atomic bomb, making it far more efficient than the alternative fissile isotopes of uranium. Werner Heisenberg and other German scientists were aware in 1941 that element number ninety-four might be a powerful nuclear explosive. However, it seems that the Allies never seriously entertained the possibility that the Nazis might be working on plutonium, while the Germans didn’t realize that the Allies had it either. If either side had known of the other’s interest and taken its implications into account in their military planning, the war might have run a very different course.

  Plutonium, an element which hardly anybody has seen, has moved swiftly to occupy the demonic space traditionally reserved for sulphur, at first because of its use in the bomb and then because of gradually dawning public awareness of the difficulty of getting rid of it. The radioactive half-life of the isotope mainly present in plutonium nuclear waste is 24,000 years, which makes planning for its safe disposal an issue that transcends normal engineering considerations. Any storage structure must be sure to outlast the Pyramids and must communicate its deadly contents in a way that is sure to be understood by civilizations that will succeed our own.

  As a budding chemist, I once applied for a summer job at what was then grandly called the Atomic Energy Research Establishment at Harwell in Oxfordshire. It was here that I had my first and only encounter with plutonium. The aura of power surrounding the element was made apparent when, as a condition of employment, I had to sign the Official Secrets Act. Was it the spartan accommodation they wanted to keep secret, or possibly the clapped-out military bus that ferried us to work? I passed the journeys knowingly reading Catch-22 as the bus coughed its way along the weedy runways of the wartime airfield where the research establishment had pitched camp after 1945.

  I found myself assigned to work in a laboratory led by a pipe-smoking figure with the windblown stride of Monsieur Hulot. The lab was designated ‘red’, the third of four levels of security. This meant I was cleared for laboratory work on dilute solutions containing plutonium and got to wear canvas overshoes which were good for gliding along the linoleum floors. Immediately, though, I felt a faint envy of those summer students who had been assigned to work in ‘purple’, the areas of highest security. The objective was to see how plutonium might be absorbed in material which could then be turned into blocks of glass. This vitrifying was thought to be a promising way to secure the waste for disposal by means and in locations never discussed. My experiment was always the same and involved pouring solutions of ‘ploot’ into columns containing the white titanium sand that was the raw material for the glass. I had no real sense of the dangers as I carried flasks of the radioactive liquid back and forth. It didn’t glow green as it does in The Simpsons, nor did I find myself carelessly leaving work with test tubes of it stuffed in my pockets as Homer Simpson does at the Springfield reactor. (I don’t recall ever being searched either.) My abiding memory is of the quiet tedium as the summer days slipped by while I transferred endless readings from the columns of sand into columns of figures on musty government stationery. It was the only time I worked in a laboratory.

  Recalling those days, I feel a nostalgic urge to add plutonium to my own periodic table. I am missing all the natural elements with atomic numbers beyond eighty-two, lead; and of those above uranium which have to be manufactured artificially I have only Seaborg’s americium, plundered from the mechanism of a domestic smoke detector where the stream of alpha particles emanating from it completes an electric circuit that is only broken if smoke blocks the path. I don’t even have a piece of the highly collectible radioactive Fiesta chinaware made in the United States from the 1930s, whose papaya orange colour arises from uranium oxide used in its glaze.

  Tracking down a specimen of the element I had once decanted in gushing quantities clearly isn’t going to be easy. The reactors and research programme at Harwell were gradually wound down during the 1990s, amid accusations of contamination of the local water supply and, ironically enough, poor waste disposal practices. AEA Technology, the private company that inherited the business of the United Kingdom Atomic Energy Authority, has perhaps wisely changed tack and positions itself, slightly improbably, as a crusading consultancy on climate change. It is unable to help me. I try British Nuclear Fuels, the outfit in charge of Britain’s nuclear waste, but find the telephone number of its director of corporate communications mysteriously cut off and later learn from its website that the company ‘has progressively divested all its businesses and run down its corporate centre’.

  The Americans seem more open about these things. Jeremy Bernstein’s book Plutonium thoughtfully reproduces the specification of the isotope 239 of plutonium that is available for purchase from Oak Ridge National Laboratory in Tennessee. It is sold as oxide powder, at least ninety-nine per cent pure. ‘This would be super weapons-grade plutonium.’ There is a telephone number and an email address, isotopes@ornl.gov. I write requesting a small sample, plaintively adding that it would be a nice reminder of the hours I spent handling plutonium solutions as a student. The reply is as prompt as it is adamant: ‘No we could not offer a sample of plutonium for any display.’

  This seems a little mean-spirited. Plutonium appears to be restricted simply because, so far as its official guardians are concerned, the only conceivable reason anybody could have for wanting it is if they are planning to add to the global total of 23,000 nuclear warheads by building their own atomic bomb. The element’s violent reputation is all that seems to matter; the fact that it is also a blameless occupant of the chemical pantheon, simply element number ninety-four, counts for nothing.

  Besides, it is not as if I want a lot of it. The one course of action left to me is to pursue this logic to its ultimate conclusion. I learn that I can in fact easily buy ‘plutonium’ over the counter as a homoeopathic remedy. The point of homoeopathic remedies of course–incomprehensible to anybody with scientific training–is that they contain only the tiniest trace, or possibly even precisely none, of the stated active ingredient. So Plutonium (Homoeopathic Proving), a liquid distributed by Helios Homeopathy of Tunbridge Wells in Kent, presumably contains an extreme dilution of some plutonium solution, perhaps of the kind I once worked with at Harwell. It seemed perverse to name a product designed to appeal to soft-headed mystics after the chemical element that has come to be seen as the distillation of the human urge for self-destruction. The Helios literature makes a wild stab at an explanation: ‘The Pandora’s box of radioactivity has been opened and has released the dark into the light,’ it says. ‘To rekindle the light our only option is to enter this dark side fully. These radioactive materials, plutonium in particular, affect the deepest levels of the human being–bone marrow, DNA, genetic structure, inner organs, and the deepest emotions.’

  I should say they do. Still, the fare to the dark side is a reasonable fourteen pounds. I dash to the Helios shop in Covent Garden.

  ‘I’d like some plutonium please,’ I ask sweetly.

  The assistant looks serious. ‘I’ll have to ask the pharmacist.’

  The what? I wonder, looking up from reading the nonsensical blurb on some remedy. There are muttered words from behind a wall of little brown bottles before the assistant returns. It seems the shop does not have any Plutonium. It’s listed on the website, I point out helpfully. Reluctantly, the ‘pharmacist’ emerges from her lair and explains that they never have it–not that it’s restricted or banned in any way, she adds. If I want to know more I will have to talk to head office. Then she breaks the shopkeeper’s code of discretion and, through narrowed eyes, demands to know why I am interested in Plutonium anyway. I say I’m a chemist, and that I’d like some plutonium for my elements collection. Perhaps I should have said I wanted it in case I’m struck by some form of late-onset radiation sickness, but it’s too late. She’s exultant at having exposed an obvious homoeopathy sceptic.

  At Tunbridge Wells, John M
organ is more helpful. ‘There is no physical presence of the element,’ he tells me. I suppose this is a homoeopath’s idea of a guarantee. ‘It is only the imprint of that element,’ made by a process of ‘molecular dilutions’ or perhaps ‘radionically’, he’s not sure. ‘It’s obviously impossible to go to a source material.’ When it was ‘proved’, the remedy was judged to be particularly efficacious in dealing with depression. But, Morgan adds brightly, ‘I suppose it could help to repair some damage if you had been exposed to plutonium.’

  Mendeleev’s Suitcases

  Blackballed by the Russian Academy of Sciences and overlooked in the first years of the Nobel Prizes, Dmitrii Mendeleev was only properly rewarded for his discovery of the periodic table nearly fifty years after his death. Then, finally, in 1955, honour was bestowed in the most fitting way, by naming after him one of the elements–the 101st–in the table. Astonishingly for this late date, Mendeleev was the first full-time chemist to be commemorated in this way. The elements that precede mendelevium in the periodic table, fermium and einsteinium, are named after physicists, reflecting their genesis in the great physics experiment known as the Manhattan Project. Later, other elements, too, would be named after physicists–Rutherford, Bohr and so on. The only elements celebrating chemists were gadolinium and curium, and even Marie Curie was as much a physicist as a chemist. It is the chemists’ misfortune that the heyday of element discovery occurred in times more concerned to see honour done to nation and to Classical ideals than to their fellows. Today, their chance seems to have gone. It is unlikely now that we will see davium, berzelium, bunsenium or ramsayon.