Niels Bohr, 1922
17 March 2023
Bohrium. element 107, symbol Bh, is named for physicist Niels Bohr (1885–1962). The element was first synthesized in 1981 at the Gesellschaft für Schwerionenforschung (Institute for Heavy Ion Research) in Darmstadt, Germany. But the discoverers originally proposed the name be nielsbohrium. And further complicating things, element 107 was not the first one for which Bohr was proposed as its namesake. Back in the 1970s, Russian researchers had proposed the name nielsbohrium for element 105.
Researchers at the Joint Institute of Nuclear Research at Dubna in Russia synthesized element 105 in 1968, and in 1973 they proposed the name nielsbohrium at a conference in Hamburg, Germany:
Recent works of several Dubna groups on the transactinide and superheavy elements are reviewed. New experiments on the volatility properties of kurchatovium and nielsbohrium halides were performed. Some fast techniques, based on gas thermochromatography of volatile inorganic species, were developed for the chemical identification of elements beyond 105 as well as for the superheavy elements.
But in 1970, a team at the University of California, Berkeley independently synthesized the element and proposed the name hahnium, after German chemist Otto Hahn (1879–1968). Credit for the discovery and the naming of the element, therefore, became embroiled in Cold War politics. In 1997, the International Union of Pure and Applied Chemistry (IUPAC) officially credited both teams with the discovery, but officially named the element Dubnium.
In 1981, while the name for element 105 was up in the air, researchers at the Institute of Heavy Ion Research in Darmstadt, Germany synthesized element 107, and in 1992 they proposed the name nielsbohrium. From Nature, 17 September 1992:
The heaviest known chemical elements—with half-lives of around 5 ms.—were finally named last week by scientists at the Institute of Heavy Ion Research in Darmstadt, Germany, where they were created by fusion reactions in the early 1980s. Element 107 is to be called nielsbohrium, after the atomic physicist Niels Bohr. Element 108, a fusion product of Pb208 and Fe58, is now hassium, named for the German state of Hessen, which supports the institute financially. Element 109–meitnerium—is a tribute to Lise Meitner, whose theoretical interpretation of Otto Hahn’s experiments was fundamental to the discovery of nuclear fission.
Unlike some previous attempts to name transuranic elements, this terminology is expected to be accepted by the international scientific community. During the cold war, element 104 was discovered concurrently in the Soviet Union and the United States, but debate continues on whether its name should be kurchatovium or rutherfordium, after the leading English and Soviet nuclear physicists of their time.
The naming was partially successful this time. In 1994, the IUPAC shortened the name to bohrium and gave it official status:
Elements 106 and 107 were named after Ernest Rutherford (New Zealand) and Niels Bohr (Denmark), respectively, to recognize their distinguished contributions to our knowledge of atomic structure. The Commission recommends the name Bohrium (Bh) for element 107, instead of the proposed Nielsbohrium, so that it conforms to the names of the other elements named after individuals.
Sources:
“Names and Symbols of Transfermium Elements (IUPAC Recommendations 1994)” Pure and Applied Chemistry, 66.12, 2421.
“News in Brief.” Nature, 359.6392, 17 September 1992, 180. ProQuest.
Oxford English Dictionary, third edition, March 2012, s.v. bohrium, n.; September 2003, s.v. nielsbohrium, n.
Zvara, I. “Studies of the Heaviest Elements at Dubna” (abstract). 24th NPAC Congress, Hamburg, 2 September 1973. OSTI.gov.
Photo credit: A. B. Lagrelius and Westphal, 1922, courtesy AIP Emilio Segrè Visual Archives, W.F. Meggers Gallery of Nobel Laureates Collection. Public domain image.