Posted on behalf of Brett Thornton and Shawn Burdette. This blog post is an epilogue to the In Your Element (IYE) article on fermium.

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When exactly was fermium first created by humans? The date for fermium’s initial production is given in some sources as October 1952, while others claim November — both dates are given for the Ivy Mike nuclear weapons test, the first time humans created elements 99 and 100. The discrepancy apparently is because Enewetak Atoll, the site of the test, lies on the other side of the International Date Line from the United States. The Ivy Mike nuclear weapons test there occurred on 1 November 1952 local time, but 31 October 1952 in the U.S. mainland.

The Ivy Mike weapons test was the first thermonuclear device — or ‘hydrogen’ bomb — and this explosion injected large amounts of radioactive debris high into the atmosphere. In the stratosphere, this debris spread over the entire globe as fallout, which was no different than any other above-ground nuclear weapons test. (Concerns about fallout was a major impetus for the the Partial Test Ban Treaty in 1963, which banned all above-ground or above-water nuclear tests). Arkansas was one of the many places the fallout landed and, in 1952, someone there was watching the sky.

After the Ivy Mike test, initial studies had revealed that the fallout contained ²⁴⁴Pu, a previously unknown plutonium isotope with a relatively large number of neutrons compared to ²³⁸U, its likely source. Glenn Seaborg at the University of California Radiation Laboratory (UCRL) received a somewhat cryptic telegram informing him that the existence of 244Pu was classified, even if it was produced by unclassified means. The UCRL group had not produced ²⁴⁴Pu yet, but they knew it was possible now. Seaborg and his UCRL group were well-known as leaders in transuranium element research, having already helped with the discoveries of plutonium, americium, curium, berkelium, and californium. If anyone stumbled across or created ²⁴⁴Pu besides the people analyzing nuclear weapon test fallout, the ‘top men’ at UCRL would be the first suspects on the list.

The knowledge that ²⁴⁴Pu existed, even if classified, was enough to get the UCRL group thinking. This probably meant that six neutrons had been almost instantaneously fused into the nucleus of ²³⁸U, much faster than was possible in a high-neutron flux reactor. This prompted UCRL researcher Albert Ghiorso to request samples of the Ivy Mike debris. Ghiorso wondered exactly how many neutrons might have been added. Was ²⁴⁴Pu the heaviest isotope in the debris or were much heavier isotopes also present? (ref. 1). Seaborg was skeptical that so many neutrons could be added to a uranium nucleus, but supported the work. This eventually led to the UCRL group finding elements 99 (ref. 2) and 100 in that fallout debris, as we describe in the fermium IYE essay.

Back in Arkansas, Paul (née Kazuo) Kuroda was interested in nuclear fallout. Kuroda was a Japanese radiochemist who had studied natural radioactive soruces in Japan. He emigrated to the United States in 1949, and worked as a postdoctoral researcher at the University of Minnesota in analytical chemistry until 1952 when he received a faculty appointment at the University of Arkansas. At Arkansas, he returned to his previous interest in radioactivity by studying the local hot springs³. Soon after starting his independent career, Kuroda came across a quote from Edward Teller, one of the principal developers of the hydrogen bomb, stating that the ”radioactive and non-radioactive elements” (the fallout) left behind by a nuclear explosion could be studied to ”learn much about the bomb”.

The Teller quotes are found in Harold Urey’s 1952 book The Planets: Their Origin and Development. Teller was paralleling the isotopic signature in bomb fallout with the isotopic signature left by the creation of the solar system and Earth. Kuroda was puzzled that Urey’s book contained no follow-up on these ideas. Kuroda later wrote ”I therefore decided to initiate my own research project on radioactive fallout from nuclear weapons tests.” (ref. 4). In 1952, Kuroda only knew about the American atomic weapons tests in the Nevada desert, and assumed that any fallout in Arkansas came from these tests. Kuroda realized that the radioactive debris from large nuclear explosions would disperse over the entire planet after being injected into the stratosphere.

In the summer of 1953, Kuroda and his co-worker Paul Damon noticed high concentrations of fission products in the Arkansas rain. They published their results quickly⁵. Their publication ”On the artificial radioactivity of rainfall”, did not go unnoticed. In the autumn of 1953, they were ordered to stop studying fallout, because ”the study of radioactive fallout by non-authorized scientists was strictly forbidden by the U.S. government as a classified military secret” (ref. 4). Damon and Kuroda apparently were mostly silent about the order to stop, but in 1954, they published a report titled ”On the natural radioactivity of rainfall”, which included the pithy statement about artificial radioactivity in rainfall: ”Presumably, considerable work is underway, but has not yet been published.” (ref. 6).

The concentrations of Es and Fm in the fallout reaching Arkansas in 1953 must have been vanishingly small, so Damon and Kuroda would almost certainly not have been able to detect the new elements. They also lacked the huge hint the UCRL group received about the ²⁴⁴Pu produced in the Ivy Mike test, which was the key insight that inspired Ghiorso’s search for elements 99 and 100 (ref. 1). On the other hand, Kuroda and Damon might have noticed ²⁴⁴Pu on their own. We like to envision Kuroda and Damon as characters in a movie asking government agents ”exactly who is investigating the fallout?” Then, like at the end of 1981 film Raiders of the Lost Ark, when Indiana Jones is assured that ”top men” are studying the Ark of the Covenant, Kuroda was being told that ”top men” were looking into it. Unlike Raiders though, the ”top men” were actually looking at the fallout samples⁷, instead of packing them in a crate and then hiding the crate in a warehouse.

Why would studying radioactive fallout be classified? Likely because, as Ghiorso and Seaborg discovered, the existence of ²⁴⁴Pu was classified. ²⁴⁴Pu is the longest-lived isotope of plutonium, and is not useful for building a nuclear weapon, but as the quote from Teller plainly said, knowledge of the fallout could reveal ”much about the bomb”. In this case, the existance of a neutron-rich isotope like ²⁴⁴Pu found from the fallout analysis might reveal something about the large neutron flux of the weapon. So ²⁴⁴Pu’s existence suggested a high neutron flux — which was key to Ghiorso’s search for elements 99 and 100. In 1953, this was definitely information best kept secret. Of course, the American government could only stop American scientists from studying fallout in rain. Papers began appearing in other countries, especially once knowledge of the hydrogen bomb tests became widely known, and the long range at which fallout could be transported was realized^8,9.

Befitting its numerologically significant position on the periodic table, fermium represents the heaviest element which has been forged in a nuclear reactor. The “fermium wall” prevents production of elements heavier than fermium by neutron absorption due to the short half-life (i.e., spontaneous fission) of ²⁵⁸Fm. To go beyond element 100, nuclear scientists had to turn to the same atom-at-a-time techniques — and the same heavy ion beams which were used to produce the first unclassified ”discovery” of fermium (see the IYE article).

In the 1950s though, you didn’t need an nuclear reactor or a convenient hydrogen bomb to find fermium — it fell from the sky.

Brett F. Thornton is in the Department of Geological Sciences (IGV) and Bolin Centre for Climate Research, Stockholm University, 106 91 Stockholm, Sweden. Shawn C. Burdette is in the Department of Chemistry and Biochemistry, Worcester Polytechnic Institute, Worcester, Massachusetts 01609-2280, USA. e-mail: brett.thornton@geo.su.se; scburdette@WPI.EDU

References

1. Ghiorso, A. Chem. Eng. News 81, 174–175 (2003). [LINK]

2. Redfern, J. Nat. Chem. 8, 1168-1168 (2016). [LINK]

3. Kuroda, P. K., Damon, P. E. & Hyde, H. Am. J. Sci. 252, 76-86 (1954). [LINK]

4. Kuroda, P. K. J. Radioanal. Nucl. Chem. 203, 591-599 (1996). [LINK]

5. Damon, P. & Kuroda, P. Nucleonics 11, 59 (1953).

6. Damon, P. & Kuroda, P. Eos, Transactions American Geophysical Union 35, 208-216 (1954). [LINK]

7. Ghiorso, A. et al. Phys. Rev. 99, 1048-1049 (1955). [LINK]

8. Miyake, Y. Papers in Meteorology and Geophysics 5, 173-177 (1954). [LINK]

9. Miyake, Y. Papers in Meteorology and Geophysics 6, 26-37 (1955). [LINK]

Note: Posted on behalf of Pekka Pyykkö, who wrote about gadolinium in our August issue‘s In Your Element article. This post comes in complement to the IYE essay – and is best read after the article. Coincidentally, there is a bit of a connection between Pekka Pyykkö and the discoverer of the rare earths: Pekka’s former position, as Professor of Chemistry, was split off as ‘the parallel chair of chemistry’ in 1908 from Gadolin’s chair of chemistry, which had been established in 1761 at the Royal Academy of Turku (Kungliga Åbo Akademi) in Finland and had been moved to Helsinki in 1828.
– Anne.

Etymology of the name ‘gadolinium’

This new ‘earth’ was first referred to by Marignac with the provisional name of ‘Y α’ (ref. S1). In 1886, it is Boisbaudran who suggested the name of ‘gadolinium, symbol Gd’, noting that Marignac has accepted the choice^S2. Circumstantial evidence from the parallel case of samarium, from the mineral samarskite, from the person Samarskii, suggests that Boisbaudran in that case thought of both the mineral and the man: “je propose le nom de samarium (symbole = Sm) dérivé de la racine qui a déjà servi à former le mot samarskite” (I suggest the name samarium (symbol Sm), from the root that has already served to form the word samarskite)^S3. The exact reference for the mineral name ‘gadolinite’ is not available, but we know that Klaproth already used it in 1801 (ref. S4).

The name Gadolin itself has its own history, which dates back two generations before the chemist Johan Gadolin. His grandfather, who came from a farm named Maunula not far from Turku, Finland, needed a surname when he entered the learned path. Re-tracing the name of his farm to the Latin ‘magnus’ (meaning great), he first adopted Magnulin as his last name. Giving it further consideration, he envisaged both the Greek Megalin and the Finnish Isolin, then finally settled on the Hebrew Gadolin, from ‘gadol’ (pictured), also meaning ‘great’. All university students at the time had to learn Greek, Hebrew and Latin.

First preparation and observation of the element

According to Jørgensen’s account^S5, Marignac separated the rare earths by repeated recrystallization of the potassium double sulphates, K₃Ln(SO₄)₃, and also reported the atomic weights, counted per one oxygen of mass 16. The atomic weight (‘équivalent’) of at least 120.5 for Gd₂O₃ in his first paper corresponds to a MGd of 156.75 — very close to the modern value of 157.25 (ref. S6). Another characteristic also reported by Marignac was that the oxide was ‘incolore’, meaning with no obvious absorption spectrum.

An interesting twist was the putative observation of phosphorescence, for gadolinium compounds, excited by electric discharges in vacuum — an experiment reported by both Crookes^S7 and Boisbaudran^S8. A bright green band at 541 and 549 nm was seen. Finally, though, Boisbaudran found that it was not connected to gadolinia and mentions a terbine impurity as a possible source for those bands^S8. This is in good agreement with recent studies of systems with Tb³⁺ ions, which do have an emission at 544 nm (ref. S9).

Pure metallic Gd was first produced by high-temperature electrolysis by Trombe in 1935 (ref. S10).

Literature

Finally, note that the original papers in French are freely available from the Gallica library gallica.bnf.fr.

References

S1. Marignac, [J-C. G. de] Ann. Chimie Phys.(Paris) 20, 535-557 (1880); Arch. Sci. Phys. Mat. (Genève) 3, 413-438 (1880).

S2. Lecoq de Boisbaudran, P.-E., C. R. Acad. Sci. 102, 902 (1886).

S3. Lecoq de Boisbaudran, P.-E. C. R. Acad. Sci. 89, 212–214 (1879).

S4. Klaproth, [M.H.] Crells Ann. 307–308 (1801).

S5. Jørgensen, C. K., Chimia 34, 381–383 (1980).

S6. Gadolin, J. Kungl. Svenska Vetenskapsak. Handl. 15, 137–155 (1794); Crells Ann. 313–329 (1796).

S7. Crookes, W., (a) Proc. Roy. Soc. 243, 77-80 (1886); (b) Nature 33, 525–526 (1886); (c) Nature, 160–162 (1886) [June 17].

S8. Lecoq de Boisbaudran, P.-E., C. R. Acad. Sci. 103, 113–117 (1886)

S9. Wang, R-F., Zhou, D-C., Qiu, J-B., Yang, Y., Wang, C., J. Alloys Comp. 629, 310–314 (2015).

S10. Trombe, F., C. R. Acad. Sci. 200, 459–461 (1935).

The illustration in the holmium In Your Element article deserves a little explanation of its contents, hence this blog post, an extended figure caption for the article.

Per Teodor Cleve (1840-1905) suggested Stockholm as the namesake for his newly discovered element in 1879 because the Stockholm area “contains minerals rich in yttria” (ref. 1) — minerals containing yttria are a source of many rare earth elements, including holmium. Stockholm was also Cleve’s hometown, and as we noted in the IYE essay, already quite rich in chemistry history. Some other reasons that Cleve might have cited are the subjects of the illustration, with an emphasis on Stockholm-related element discoveries.

The raven — Korpen pharmacy

The raven refers to Korpen (the raven) pharmacy, located in the old town of Stockholm. This pharmacy was founded in 1674 by Jurgen Brandt, a German immigrant to Sweden. Coincidentally, Jurgen Brandt was the father of Georg Brandt (1694-1768), the first Swede to discover a chemical element (cobalt). The apothecary was at first called Örnen (the eagle) apothecary, but after being unsuccessful in its first location south of central Stockholm, the pharmacy was moved within a few years to the old town (Gamla stan); there it also received its present name, Korpen.

In 1768, Carl Wilhelm Scheele (1742-1786) moved to Stockholm and worked at Korpen for a time. Dissatisfied with his career progress in Stockholm, he moved to Uppsala, where he came in contact some of the more important chemists of the time… and where he discovered oxygen. Today, another pharmacy in Stockholm is named for Scheele.

“STOCKHoLM” façade — Ugglan pharmacy

Pharmacies continued to be prime places for Swedish chemists to work in the 19th century; at Stockholm’s Ugglan (the owl) pharmacy a young Carl Gustaf Mosander (1797-1858) was apprenticed. Mosander later went on to work at the Swedish Museum of Natural History in Stockholm. While at the museum he discovered of the elements lanthanum, terbium, and erbium. In the drawing, the façade with false columns and the word STOCKHoLM — with holmium’s symbol highlighted — are modelled after present-day front of Ugglan pharmacy (the actual sign reads “APOTEKET UGGLAN.”).

Portrait in window — Berzelius

The portrait in the shop window is Jöns Jacob Berzelius (1779-1848), perhaps the most famous Swedish chemist of all time, whose work was vital in the discoveries of cerium, selenium, silicon, zirconium, and thorium. (Berzelius is not always credited was discovering zirconium: he was the first to obtain zirconium metal, but its existence had been suggested decades earlier by Martin Klaproth.) Berzelius and his students combined to contribute to the discoveries of 10 elements (ref. 2).

Dynamite — Alfred Nobel

The fuse and dynamite bundle refers, of course, to the late 19th century industrial chemist, Alfred Nobel (1833-1896). Nobel patented dynamite in 1867, and had factories near Stockholm. Nobel’s namesake element, nobelium, was the most recent element discovery to be claimed by Stockholm scientists (ref. 3); though the name stuck, the discovery credit did not (ref. 4).

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Brett F. Thornton is in the Department of Geological Sciences, and Bolin Centre for Climate Research, Stockholm University, 106 91 Stockholm, Sweden.

Emma S. Karlsson is in the Department of Analytical Chemistry and Environmental Science, and the Bolin Centre for Climate Research, Stockholm University, 106 91 Stockholm, Sweden.

Shawn C. Burdette is in the Department of Chemistry and Biochemistry, Worcester Polytechnic Institute, Worcester, Massachusetts, 01609-2280, USA.

References

1. Cleve, P. T. Sur deux nouveaux éléments dans l’erbine. Comptes Rendus Hebdomadaires Des Seances De L Academie Des Sciences 89, 478–480 (1879).
2. Trofast, J. Berzelius’ Discovery of Selenium. Chemistry International 33, 16–19 (2011).
3. Fields, P. R. et al. Production of the new element 102. Physical Review 107, 1460–1462, doi:10.1103/PhysRev.107.1460 (1957).
4. Thornton, B. F. & Burdette, S. C. Nobelium non-believers. Nature Chemistry 6, 652–652, doi:10.1038/nchem.1979 (2014).

Posted on behalf of Brett Thornton and Shawn Burdette. This blog post contains more information and references about the discovery of nobelium, and accompanies the nobelium In Your Element (IYE) article. Though it somewhat stands alone, it is best read after reading the IYE essay.

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Up until element 100, the United States had a monopoly on the production of transuranic elements. That monopoly came to an end after element 100, where the American group at the University of California Berkeley barely managed to publish an account¹ of creating element 100 before a group in Stockholm published a similar feat². (Although it is worth noting that the Berkeley team had been delayed by Cold War secrecy).

Elements 101-106 were all disputed discoveries, to greater and lesser degrees, between the American (Berkeley) and Soviet (Moscow, later Dubna) research teams³. Element 102, nobelium, is unique in that the dispute was tripartite — a Swedish–American (Argonne, not Berkeley)–British research team had the first claim to the element^4,5. They named it too, giving nobelium the sometimes-declared-ignoble distinction of having been named before it was ‘properly’ discovered, and also not being named by its ‘true’ discoverers.

As discussed in the IYE article, element 102, nobelium, was particularly difficult to discover, partly owing to the surprising stability of No²⁺ in aqueous solutions⁶. Ytterbium, directly above element 102 on the periodic table, also has a prominent 2+ oxidation state, unusual for lanthanides (and actinides). However, in the 1950s, Glenn Seaborg’s ‘actinide hypothesis’, placing the actinides as a new group beneath the lanthanides, was still a relatively new idea⁷; a few years earlier, element 102 might have been guessed to lie below polonium.

And, at first, the 3+ oxidation state for later actinides was the only one forseen. In the actinide hypothesis paper⁷ of 1946 Seaborg wrote: ‘Deductions from work on the tracer scale with these isotopes lead to the conclusion that the III oxidation state is the most stable and by far the most important state for these elements in aqueous solution.‘ In the following decade, actinide separation methods were refined, and by 1956 a general, powerful method was established using cation exchange columns⁸. Consistently, the oxidation state of later actinides in aqueous solution was proving to be 3+. Of course, this method had not been tried on any undiscovered elements, and was only tested up to mendeleevium, element 101. The Stockholm group expected the method to work for element 102, but unbeknownst at the time, nobelium prefers the 2+ state in solution, so the method fails. The ²⁴⁴Cm + 65-100 MeV ¹³C reaction performed in Stockholm may have produced element 102, but their chemical separation method failed to isolate it. Initially, the Berkeley group was also using this separation method based on 3+ ions. And they were quite certain of their own early results: ‘the name nobelium for element 102 will undoubtedly have to be changed,‘ Seaborg commented⁹ in 1959. The Stockholm group’s rebuttal in 1959 did not at all satisfy the Berkeley group.

By the mid-1960s, the priority fight over the discovery of element 102 was clearly between the American (Berkeley) and Soviet (Dubna) groups. Following self-admittedly weak reports¹⁰ in 1958, the first strong Soviet claims to element 102 appeared¹¹ in 1964, and were substantially strenghtened in 1966, and were in contrast to earlier Berkeley results. In response, the Berkeley group had performed comprehensive new experiments, produced and characterized many isotopes of element 102, including the successful production of ²⁵²No and ²⁵³No using the ²⁴⁴Cm + 62-74 MeV ¹³C reaction¹². Their methods were now vastly improved from the late 1950s. Remarkably, this March 1967 paper from the Berkeley group makes no acknowledgement that they were using the same reaction, with similar products, as the Stockholm group had claimed to produce nobelium a decade earlier. (The Stockholm group had claimed ²⁵¹No or ²⁵³No; both groups varied the ¹³C beam energies in numerous tests.) Of course, it was clear by now that the Stockholm group’s assignment of half-life and alpha-energies had been incorrect. It was also clear by 1967 that the Berkeley group’s early isotope and half-life assignments were incorrect as well. The Russian team did not shy away from pointing this out, later calling the Berkely explanations ‘backdated’, and published a flowchart to helpfully explain how their mid-1960s experiments had refuted all earlier Berkeley element-102 experiments, and subsequent Berkeley reports had merely confirmed the Dubna reports¹³.

Later, in September 1967, the Berkeley group further set out their claim for element 102’s discovery in the magazine Physics Today. On the Stockholm experiments, they wrote: ‘Our group made such an attempt soon thereafter (1958) at the Lawrence Radiation Laboratory. With great persistence we tried to reproduce the results of the Stockholm work […] we were unable to produce any nuclei of element 102 with the reported properties (8.5-MeV alpha particles and 10-min half-life). Under the superior conditions of these repeated experiments we estimated that we should have produced and observed at least 100 such nuclei in each experiment if the Nobel Institute findings were correct.‘¹⁴

Scientists tend to write little without meaning, and though we can’t know the intent for sure, the statement that the Berkeley group was ‘unable to produce any nuclei of element 102 with the reported properties (8.5-MeV alpha particles and 10-min half-life)’, very explicitly does not rule out that they had produced element 102 using the same ²⁴⁴Cm + ¹³C reaction as the Stockholm group. And by September 1967, they had published that very claim. Yet once again, the Berkeley group made no mention that their own experiments using the same reaction (and improved conditions) as the Stockholm group, had actually created element 102. Much of the 1967 Berkeley articles are dedicated to explaining how the old Berkeley results antedate any production of element 102 by the Soviet group in Dubna. It is curious, too, that the Berkeley group had backed off from renaming the element.

In a posthumous publication, Flerov (he died in 1990) wrote: ‘[T]he debate between the two groups in Stockholm and Berkeley has not been finished’¹³; Flerov seemed to imply that the Stockholm and early Berkeley experiments contained so many errors that their results could hardly ever be satisfactorily explained.

IUPAC now credits^3,15,16 solely the Dubna group with first creating element 102 in 1966, and the commonly told story about element 102 is that the Stockholm group didn’t actually create the element which they named. The initial response to the IUPAC decision by Berkeley was…strident¹⁷. Unsurprisingly, the Dubna group quickly praised the IUPAC decision¹⁷. In later years, the Berkeley group belatedly acknowledged the work of the Dubna group, allowing them as co-discoverers. They referred¹⁸ to the Stockholm experiments as a ‘fiasco’. The naming of the element by the Stockholm group is less bothersome when one realizes that, in fact, they may have created element 102 in 1957, before anyone else. But the Stockholm group’s unsuccessful isolation and characterization of element 102 set off a complex, decade-long quest for the element in Berkeley and Dubna, and a far longer series of arguments over who actually discovered the element.

Brett F. Thornton is in the Department of Geological Sciences (IGV) and Bolin Centre for Climate Research, Stockholm University, 106 91 Stockholm, Sweden. Shawn C. Burdette is in the Department of Chemistry and Biochemistry, Worcester Polytechnic Institute, Worcester, Massachusetts 01609-2280, USA. e-mail: brett.thornton@geo.su.se; scburdette@WPI.EDU

References

1. Harvey, B. G., Thompson, S. G., Ghiorso, A. & Choppin, G. R. Phys. Rev. 93, 1129–1129 (1954). [LINK]

2. Atterling, H., Forsling, W., Holm, L. W., Melander, L. & Åström, B. Phys. Rev. 95, 585–586 (1954). [LINK]

3. Wilkinson, D. H. et al. Pure Appl. Chem. 65, 1757–1814 (1993). [LINK]

4. Fields, P. R. et al. Phys. Rev. 107, 1460–1462 (1957). [LINK]

5. Fields, P. R. et al. Arkiv for Fysik 15, 225–228 (1959).

6. Hoffman, D. C. J. Radioanal. Nucl. Chem. 291, 5–11 (2012). [LINK]

7. Seaborg, G. T. Science 104, 379–386 (1946). [LINK]

8. Choppin, G. R., Harvey, B. G. & Thompson, S. G. J. Inorg. Nucl. Chem. 2, 66–68 (1956). [LINK]

9. Seaborg, G. T. J. Chem. Educ. 36, 38-44 (1959). [LINK]

10. Flerov, G. N. et al. Doklady Akademii Nauk Sssr 120, 73–75 (1958).

11. Donets, E. D., Shchegolets, V. A. & Ermakov, V. A. Atomnaya Energiya 16, 197-207 (1964). [LINK]

12. Ghiorso, A., Sikkeland, T. & Nurmia, M. J. Phys. Rev. Lett. 18, 401–404 (1967). [LINK]

13. Flerov, G. N. et al. Radiochim. Acta 56, 111–124 (1992). [LINK]

14. Ghiorso, A. & Sikkeland, T. Phys. Today 20, 25–32 (1967). [LINK]

15. Donets, E. D., Shchegolev, V. A. & Ermakov, A. Atomnaya Energiya 20, 223–230 (1966). [LINK (pdf)]

16. Zager, B. A. et al. Atomnaya Energiya 20, 230–232 (1966).

17. Ghiorso, A. et al. Pure Appl. Chem. 65, 1815–1824 (1993). [LINK]

18. Hoffman, D. C., Ghiorso, A. & Seaborg, G. T. The Transuranium People: The Inside Story. (Imperial College Press, 2000). [LINK]

Our ‘in your element’ feature is still alive and well, the articles are still freely available online, and the periodic table here is still being updated. Over the last few months a few more squares in that periodic table have been filled in with contributions from several authors.

In February, Anders Lenartsson from Chalmers University of Science and Technology argued that there are many reasons to disagree with one of his former professors, who said that “you’ll never impress me with zinc”.

Neatly continuing on the short-lived and entirely unintentional theme of ‘elements beginning with Z’, in March, John Emsley explained that zirconium has more wide-ranging applications than the use of its silicate, cubic zirconia, in fake gemstones.

In the April issue, Claude Piguet from the University of Geneva illuminated the convoluted history of erbium, and told us how it has carved out a niche for itself in photonics.

In the May issue, which came online a few days ago, Eric Ansoborlo from the French Alternative Energies and Atomic Energy Commission shared some interesting nuggets on polonium, including a health warning for smokers: polonium is not only extremely radiotoxic, but the small amounts that are found in nature are also known to accumulate in tobacco plants.

The articles themselves do not come with any such health warnings though, so do take a look at what other fascinating facts are contained within!

Some of you may have noticed that I haven’t posted about our ‘In your element’ pieces for a couple of months — this is partly because things have been very busy over at the journal [I know I always say that… but it’s because it’s always true!] and also partly because these articles are now freely available online.

After the New Year, we might stop posting about them altogether and let you go to the articles directly — but we’ll continue to update the periodic table here. And before that happens, let me share with you a few snippets from our three most recent elements.

In our November issue, science writer John Emsley took a detailed look at just how essential manganese is for life. Because the body human needs so little of it (a person contains on average of 12 mg) this only came to our attention in the 1950s, but manganese is present in many enzymes. It is the manganese superoxide dismutase, for example, that protects cells against the superoxide radical O₂⁻ (through dismutation into oxygen and hydrogen peroxide). Read the article to find out how manganese also turned up at the bottom of the sea.

In the December piece, geochemist Joel Blum from the University of Michigan, who works on understanding mercury’s behaviour in the environment, discussed why he fell under its spell. The metal that is liquid at room temperature, and particularly dense, has long captivated chemists and before them alchemists. Yet it is notoriously dangerous: mercury is a neurotoxin in most of its form, toxic by ingestion, inhalation and through the skin, both through chronic or acute exposure. It is mercury poisoning that caused hatters to develop dementia, owing to a step in the process of making felt hats that used a mercuric nitrate solution (Hg(NO₃)₂·2H₂O) — their erratic behaviour led to the phrase ‘mad as a hatter’. The risks of mercury exposure were recognized at the end of the 19^th century.

And the January article, which went live earlier this week, saw Markku Räsänen from the University of Helsinki reminisce about making the first neutral argon compound, HArF, in 1999 — also just before Christmas —  together with Mika Pettersson and Jan Lundell (now both professors in the University of Jyväskylä) and Leonid Khriachtchev (in the Räsänen group). Argon and the other noble gases have shown over the past several years that they can indeed form compounds, including hydrides. To what extent? We don’t know for sure yet. Theoretists and experimentalists, to your computers and benches!

Editor’s note: Earlier this year our ‘In your element’ section featured an article about neon written by Felice Grandinetti from the University of Tuscia (you can also find a write-up here by yours truly). We recently received a letter from Roald Hoffmann from Cornell University, which we are publishing here on the blog, with a reply from Felice Grandinetti. Feel free to add your own thoughts in the comments section below.

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To the Editor:

Felice Grandinetti’s comment on the singularity of supremely inert Ne, and his suggestion of having He head group 2 of Mendeleyev’s Table are on the mark¹. But he should have mentioned the people who suggested that before him — Henry Bent² and Eric Scerri³ have argued over the years for this placement. And Wojciech Grochala likewise, supporting his argument with detailed quantum mechanical calculations on diverse He and Ne containing molecules^4,5. Their well-thought-through arguments deserve reference.

Roald Hoffmann, Cornell University

References

1. Grandinetti, F. Nature Chem. 5, 438 (2013). [Link]

2. Bent, H. New Ideas in Chemistry from Fresh Energy for the Periodic Law (AuthorHouse, 2006). [Link]

3. Scerri, E. R. The Periodic Table: Its Story and Its Significance (Oxford University Press, 2007). [Link]

4. Grochala, W. Pol. J. Chem. 83, 87–122 (2009). [Link to journal website]

5. Grochala, W. Phys. Chem. Chem. Phys. 14, 14860–14868 (2012). [Link]

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Felice Grandinetti replies:

In reply to the letter by Roald Hoffmann:

My essay on neon chemistry intended to be an entertaining recognition of salient facts, systems, and concepts. The supreme inertness of Ne and the actual position of He in the periodic table are, in particular, “hot” topics, well highlighted before me by the scientists mentioned by Roald Hoffmann in his comment. I at present share the suggestion that neon is the most inert element, based also on my own experience in the theoretical investigation of noble gas compounds. The competition between He and Ne as the most inert element certainly invites further investigation, and I hope that this blog may be the place for future debate.

Felice Grandinetti, University of Tuscia

Apologies for posting this a little late (again)… In the ‘in your element’ piece from our October issue, Somobrata Acharya from the Indian Association for the Cultivation of Science, Kolkata, recounts the role of lead throughout history. Element 82 has been known for thousands of years, and widely used owing to the fact that it is abundant, easy to extract, malleable and therefore easy to manipulate.

Lead was known to the ancient Greeks, somewhat confusingly under the name molybdos; it does make sense though, as they didn’t distinguish lead ores and molybdenum ones. In a similar manner, lead and tin were called plumbum nigrum (black lead) and plumbum candidum or album (bright lead), respectively, until the 16th century. Lead also appears in the Old Testament — I found these two incidences on the Elementymology & Elements Multidict website:

“Thou didst blow with thy wind, the sea covered them: they sank as lead in the mighty waters.” (Exodus 15, 10).

“Only the gold, and the silver, the brass, the iron, the tin, and the lead, Every thing that may abide the fire, ye shall make it go through the fire, and it shall be clean” (Numbers 31, 22-23).

This heavy metal was widespread in the Roman Empire, from water pipes to jewellery to sweetener production (in which lead acetate, also known as ‘lead sugar’ was used). It is toxic to humans though, damaging the nervous system and interfering with various organs and tissues. Lead poisoning can occur through either acute or chronic exposure — the latter being the most common one. It is very interesting that ancient Romans, Greeks and Chinese had noticed lead was toxic, yet it wasn’t until the 20th century that its use became strictly regulated, and leaded petrol and paint banned from sale.

The article also recounts some great discoveries involving this pervasive element — read for example in what way lead participated to the development of the radio, infrared technology, and understanding the quantum confinement effect.

I’ve had a rather busy summer, and apologize for not posting earlier about last month’s ‘in your element’ piece. Our before-latest article sees Barbara Finlayson-Pitts from the University of California, Irvine take a look at chlorine. I’m happy to say that this element, which chemists and non-chemists alike are well acquainted with, completes our first family of the periodic table!

The first report of chlorine has some fantastic and charming old chemical language in it (I think I may have already mentioned my penchant for archaic terms): Carl Wilhelm Scheele noticed that reacting “brunsten” with “muriatic acid” led to a yellowish green gas — check in the article just what those reactants were. At the time, the gas was referred to as “oxymuriatic acid”, a compound of oxygen and muriatic acid. It was Sir Humphry Davy that later identified it as a new element, and named it chlorine after its colour.

Element 17 is abundant, and has found many applications, for better (such as for bleaching and disinfecting water) or for worse (for example, chlorinated compounds have been used as chemical weapons). One aspect discussed in the article, which must not be neglected, is its atmospheric chemistry. The chlorofluorocarbons (CFCs) of aerosols and refrigerants have been linked to much damage in the atmosphere. Other sources of element 17 that contribute to its atmospheric chemistry are increasingly being identified. NaCl particles from seas and oceans, and dust from alkaline dry lakes, also contains chlorine that goes on to react with gases in the atmosphere; surprisingly, chlorine chemistry is also observed in continental regions.

In any case, don’t let the fact that “these atmospheric processes are incredibly intricate and difficult to study” stop you, Barbara Finlayson-Pitts emphasizes that “elucidating their chemistry is critical to quantitative predictions of processes, and in turn reducing or overcoming undesirable effects.”