Chemistry

An Overview about the Chemical Element Bohrium



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Bohrium

Symbol: Bh

Atomic Number: 107

Atomic Mass: 272.0 amu (atomic mass units)

Melting Point: Unknown

Boiling Point: Unknown

Number of Protons: 107

Number of Electrons: 107

Number of Neutrons: 165

Classification: Transition Metal (Man Made)

Crystal Structure: Unknown

Density @ 293 K: Unknown

Color: Unknown

Bohrium is a radioactive man made super-heavy element. The super-heavy elements are made by bombarding the atoms of one element with the ions of another element. Bohrium was produced by the bombardment of a rotating cylinder of bismuth-209 with the ions of chromium-54 to produce bohrium-262. Each atom of bohrium produced also yielded a free neutron.

The first scientists reporting the making of element 107 were based at the Joint Institute for Nuclear Research in Dubna, Russia in 1976. These experiments were confirmed in 1981 by the scientists at the Gesellschaft fur Schwerionenforschung (GSI) in Darmstadt, Germany under the leadership of Peter Armbruster and Gottfried Munzenber.

Element 107 has had a number of names. Originally it was named using the International Union for Pure and Applied Chemistry (IUPAC) naming system. This system where each syllable stands for a number gave the name unnilseptium (un-nil-sept meaning 1-0-7) and the symbol Uus. The German scientists at Darmstadt proposed naming it Nielsbohrium, with the symbol Ns, after the Danish physicist Niels Bohr. IUPAC while agreeing to name the element after Niels Bohr had a problem with the use of the scientists first name as all other elements named after scientists used only the surname. Eventually it was agreed that element 107 would be named bohrium, with the symbol Bh, after the Danish scientist.

All of the isotopes of Bohrium are unstable with very short half lives. The longest half life of 9.8 seconds belongs to bohrium-272. Bohrium-272 decays to form dubnium-268 by alpha decay. At present there are ten isotopes of bohrium recognized some of these have not had their half lives measured.

Because only a few atoms of bohrium have ever been produced its bulk properties such as density, boiling point and melting point are unknown. From its position in the periodic table it is theorized that it would be metallic and silver, white or grey in color.

Recently scientists at the Paul Scherrer Institute in Switzerland claim to have produced two new isotopes borhrium-266 and bohrium-267 by bombarding berkelium-249 atoms with neon-22 ions. Within this experiment they also feel that bohrium formed the compound bohrium oxychloride.

With so few atoms being produced combined with its radioactivity and short half life it is unlikely that bohrium will ever have any uses outside of scientific research.

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