Bohrium Traditional Cache

Bohrium is a chemical element with the symbol Bh and atomic number 107 and is the heaviest member of group 7 (VIIB). It is a synthetic element whose most stable known isotope, ²⁷⁰Bh, has a half-life of 61 seconds. Chemical experiments have confirmed bohrium's predicted position as a heavier homologue to rhenium with the formation of a stable +7 oxidation state.

The first convincing synthesis was in 1981 by a German research team led by Peter Armbruster and Gottfried Münzenberg at the Gesellschaft für Schwerionenforschung (Institute for Heavy Ion Research, GSI) in Darmstadt using the Dubna reaction.

In 1989, the GSI team successfully repeated the reaction during their efforts to measure an excitation function. During these experiments, ²⁶¹Bh was also identified in the 2n evaporation channel and it was confirmed that ,²⁶²Bh exists as two states - a ground state and an isomeric state. The IUPAC/IUPAP Transfermium Working Group (TWG) report in 1992 officially recognized the GSI team as discoverers of element 107.

Historically element 107 has been referred to as eka-rhenium. The German group suggested the name nielsbohrium with symbol Ns to honor the Danish physicist Niels Bohr. The Soviet scientists had suggested this name be given to element 105 (which was finally called dubnium) and the German team wished to recognize both Bohr and the fact that the Dubna team had been the first to propose the cold fusion reaction. There was an element naming controversy as to what the elements from 104 to 106 were to be called; the IUPAC adopted unnilseptium (symbol Uns) as a temporary, systematic element name for this element. In 1994 a committee of IUPAC rejected the name nielsbohrium since there was no precedence for using a scientist's complete name in the naming of an element and thus recommended that element 107 be named bohrium. This was opposed by the discoverers who were adamant that they had the right to name the element. The matter was handed to the Danish branch of IUPAC who voted in favor of the name bohrium. There was some concern however that the name might be confused with boron and in particular the distinguishing of the names of their respective oxo-ions bohrate and borate. Despite this, the name bohrium for element 107 was recognized internationally in 1997. The IUPAC subsequently decided that bohrium salts should be called bohriates.