Nobelium No

Discovery

In 1957 an international team based at the Nobel Institute of Physics in Stockholm, with participants from Argonne National Laboratory in the United States and the Harwell laboratory in Britain, reported making element 102 by bombarding curium with carbon-13 ions. They proposed the name nobelium, and IUPAC accepted it almost at once.

In 1958, however, a Berkeley team tried to repeat the experiment and could not reproduce it. The Berkeley group then claimed a different isotope made with its new linear accelerator, but that interpretation also turned out to be partly wrong. Meanwhile Georgy Flerov's group at Dubna in the Soviet Union carried out experiments from 1958 onwards and, between 1963 and 1966, published results that firmly identified several isotopes of element 102.

The argument over credit dragged on for decades. In 1992 a joint IUPAC–IUPAP working group concluded that the Dubna work constituted the definitive discovery. The Soviet side had at one point proposed the name 'joliotium', but in 1997 IUPAC confirmed the long-established name nobelium.

Origin of the name

The element honours Alfred Nobel, the Swedish chemist, inventor and founder of the Nobel Prizes, because the first claim came from the institute bearing his name. The symbol is No. It is a rare case in which the discovery claim was rejected but the name it came with was kept.

Main uses

• Basic research: Nobelium is made only atom by atom, so it serves purely scientific purposes. Most actinides are most stable in the +3 state in water, but nobelium is unusual in favouring +2, a consequence of the stability of its completely filled 5f shell of 14 electrons.
• Atomic physics: Laser spectroscopy on just a handful of atoms has been applied to nobelium, opening the way to measuring the electronic structure of superheavy elements directly.

Isotopes

Nobelium has no stable isotopes. The longest-lived, nobelium-259, has a half-life of about 58 minutes. Chemistry experiments usually use nobelium-255 (about 3.1 minutes), because it can be produced in larger numbers. Nobelium-254, characterised at Dubna, has a half-life of about 50 seconds.

In everyday life

Nobelium does not occur in nature and plays no part in everyday life. It has never been made in weighable amounts; experiments deal with tens to thousands of atoms at a time. Although radioactive, it poses no realistic exposure risk outside the few laboratories that produce it.