ununbium

Ununbium was the systematic IUPAC name for the chemical element with atomic number 112. It is a synthetic, highly radioactive metal that has not been observed in nature and exists only for brief moments in particle accelerators. As a member of group 12 in period 7, it is the heaviest known element in the zinc–cadmium–mercury–copernicium sequence, though its properties are largely theoretical due to its extreme instability.

The first synthesis of ununbium was reported in 1996 by researchers at the GSI Helmholtzzentrum für Schwerionenforschung in Darmstadt, Germany. In the experiment, a beam of 70Zn bombarded a 208Pb target, producing the isotope 277Cn via the reaction 208Pb(70Zn, n)277Cn, with the product decaying through alpha emissions in a matter of milliseconds. The discovery team assigned the temporary name ununbium (symbol Uub) under the IUPAC naming scheme for undiscovered elements.

In 2010, IUPAC approved the official name copernicium (symbol Cn) for element 112, honoring Nicolaus Copernicus. The older name ununbium remains in historical literature as the element’s temporary identifier.

Chemically, copernicium is expected to resemble a heavier member of group 12, behaving as a post-transition metal with properties influenced by relativistic effects. However, the extreme short half-lives and minuscule production rates of observed isotopes have limited experimental measurements, so many chemical properties are not well established and are primarily subjects of theoretical study. Copernicium has no practical applications and is studied mainly for insights into the chemistry of superheavy elements and nuclear physics.