Overview

Bohrium was first created in 1981 at the GSI laboratory in Darmstadt, Germany, by a team led by Peter Armbruster and Gottfried Munzenberg, by fusing bismuth and chromium nuclei. It was named after the Danish physicist Niels Bohr, one of the founders of quantum theory and of the modern understanding of atomic structure. Bohrium is an intensely radioactive synthetic metal, studied only atom by atom. Its isotopes last only seconds at most, but a landmark experiment on just a few atoms confirmed that bohrium forms a volatile oxide like its lighter relatives rhenium and technetium, placing it firmly in group seven.

The GSI team's success with bohrium and several of its neighbours rested on a technique called cold fusion, in this context an entirely legitimate nuclear-physics method using carefully chosen, gently colliding heavy-ion beams to fuse nuclei with far less excess energy than earlier hot-fusion approaches, which let the resulting compound nucleus survive intact long enough to be detected rather than immediately breaking apart; the method became the German laboratory's signature contribution to the discovery of elements 107 through 112. Only a handful of bohrium atoms have ever been made, and each must be identified within seconds through its characteristic chain of radioactive decays.