Hidden Hassium

in your element Corrected: Author Correction Hidden hassium From its scarcity to political intrigue over naming conventions, element 108’s story describes how international cooperation overcame the limits of nuclear science, says Michael Tarselli. casual aside uttered by Nottingham osmium one expects it might be a solid, but Professor Sir Martyn Poliakoff during this is tough to tell from a handful of atoms Ahis Periodic Table of Videos series stuck to a silicon detector. When you have (http://www.periodicvideos.com/videos/108. only traces of a specific element, how do htm) reflects a general feeling: “Hassium you investigate its properties? Invent some … I know nothing about hassium. Shall we fairly specialized lab equipment. Hassium make something up?”. Among the already is tough to separate away from other super- little-known super-heavies, element 108 heavies and by-products of the fusion doesn’t have the controlled reactivity of a reaction; specialized detectors were built to seaborgium atom, or the relative stability study its characteristic α -decay and probe its of fermium — the longest-lived isotope is reaction chemistry. In 2002 the GSI, JINR, 257Fm with a net 100 day half-life, and 252Fm the Lawrence Berkeley National Laboratory is believed to resist spontaneous fission and seven other institutions joined forces to 1 rather well , though it undergoes α -decay. Credit: michal812 / Alamy Stock Photo create seven atoms of hassium. Those were In contrast the half-life of hassium’s most then pushed through a stream of oxygen stable isotope, 270Hs, is only a few seconds. to yield a highly volatile oxide with similar Estimates for the total number of hassium calcium or iron to be fired, pushing back the properties to ruthenium and osmium atoms created so far run from a few dozen limit to 118… so far. The first hassium atoms tetroxides — “presumably HsO4”, whose to as many as 100 atoms. Ever. were synthesized by bombarding a lead single 269Hs atom was identified by α -decay5 How were those lone atoms produced? Let’s target with iron atoms. The process was later In a 2011 Science Perspective6, nuclear rewind to 1984. Major nuclear research was optimized, and firing 26Mg at a target made physicist Walter Greiner wryly suggested emerging from three countries, two of which of 248Cm gave 270Hs — which was dubbed the that neutron-rich nuclei, such as hassium, had outmoded names: West Germany, the doubly magic isotope4. might be feasibly made by setting off “two USSR and the USA. Back then, element 108 Along with new elements came numerous or three nuclear explosions near a suitably was simply known as Uno for ‘unniloctium’, priority disagreements, and thus naming protected target buried deep underground.” literally meaning ‘one-zero-eight’ according to controversies — so much so that the As multiple global treaties prohibit this, we a system of numerical roots adopted in 19792. International Unions of Pure and Applied will have to keep relying on technologies Since the 1940s, scientists had prepared novel Chemistry and Physics (IUPAC and IUPAP) such as bombarding accelerator targets with transactinides by bombarding uranium with created the Transfermium Working Group, in neutron-rich beams of 48Ca or 58Fe. Even if we neutron beams. This approach, however, only which scientists from the three main heavy- have to wait a few more decades for the next works up to element 100 (fermium). The team element-discovering nations first oversaw the generation of nuclear scientists to produce at the Joint Institute for Nuclear Research recognition process for elements 101–109. enough hassium to fill in the blank spaces of (JINR) in Dubna, USSR (now Russia), led In 1994, this group advanced the names our knowledge, it’s probably for the best. ❐ by actinide heavyweight Yuri Oganessian, hahnium and meitnerium for elements then pioneered the techniques of ‘cold’ fusion 108 and 109, for nuclear fission discoverers Michael A. Tarselli (collisions of two early elements such as iron Otto Hahn and Lise Meitner, respectively. NIBR Informatics (NX), Novartis Institutes for and bismuth) and 'hot' fusion (using actinide Meitnerium was adopted, but for 108 the BioMedical Research, Cambridge, MA, USA. radionuclides as the targets). suggestion of the German team, led by Peter e-mail: [email protected] In hot fusion, researchers bombard Armbruster and Gottfried Münzenberg, Published online: 22 March 2018 a heavy target such as einsteinium or was the one ratified in 1997: hassium, which https://doi.org/10.1038/s41557-018-0037-4 plutonium with a beam of lighter elements honours the German state of Hesse (whose such as carbon or oxygen. This early map and coat of arms are pictured). References 3 1. Staszczak, A., Baran, A. & Nazarewicz, W. Preprint at technique, according to Peter Armbruster Perhaps the most tantalizing aspect https://arxiv.org/abs/1208.1215 (2012). from Germany’s GSI Helmholtz Centre of hassium is that it’s nearly unexplored. 2. Chatt, J. Pure Appl. Chem. 51, 381–384 (1979). for Heavy Ion Research, worked fine up to We still don’t know many of its physical 3. Armbruster, P. & Hessberger, F. P. Making New Elements. Scientifc element 106 (seaborgium). New equipment properties — melting point, boiling point, American (September 1998); http://go.nature.com/2GWiHyG 4. Dvorak, J. et al. Phys. Rev. Lett. 97, 242501 (2006). later allowed beams of heavier nuclei such as pressure or heat capacity. Looking at its 5. Düllmann, Ch. E. et al. Nature 418, 859–862 (2002). group 8 cousins iron, ruthenium and 6. Clery, D. Science 333, 1377–1379 (2011). Db Sg Bh Hs Mt Ds Rg Cn Nh Fl Mc Lv Ts Og 119120 121122 123124 125 482 NATURE CHEMISTRY | VOL 10 | APRIL 2018 | 482 | www.nature.com/naturechemistry © 2018 Macmillan Publishers Limited, part of Springer Nature. All rights reserved. © 2018 Macmillan Publishers Limited, part of Springer Nature. All rights reserved..

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