Bohrium

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.

Bohrium honours Niels Bohr, whose model of the atom, with its electrons arranged in shells, underlies the very structure of the periodic table and explains why the elements recur in families as they do. The name was originally proposed as nielsbohrium, partly to distinguish it in the tangle of the naming disputes, before being shortened to the standard bohrium.

There is a fitting logic in giving Bohr's name to a superheavy element, since it was his atomic theory that let chemists predict where such elements should sit and how they might behave. Bohrium has no ancient or esoteric tradition, being a synthetic element of the 1980s; its interest lies in honouring one of the architects of the quantum atom, and in the extraordinary experimental feat of making and identifying a few atoms of an element that endures for only a fraction of a second.

The institute Bohr founded in Copenhagen, now called the Niels Bohr Institute, became one of the great meeting places of early twentieth-century physics, training or hosting a remarkable number of future Nobel laureates and shaping the development of quantum mechanics as thoroughly as any single institution in the field's history. Bohr also fled Nazi-occupied Denmark for Sweden and then the United States during the Second World War, later contributing to the Manhattan Project before returning home once the occupation ended.