Copernicium

Copernicium is in group 12 and is a metal, but calculations indicate that its outer electrons are strongly bound to the atom. This could make it less reactive and more volatile than other metals of its group, with a behavior that in some aspects recalls that of noble gases. However, only a few atoms have been produced, so its macroscopic properties have not been measured directly.

Nicolaus Copernicus revolutionized the history of human thought by publishing in 1543 his heliocentric model, placing the Sun at the center of the solar system and the Earth in orbit around it. The GSI discovery team proposed 'copernicium' to honor the brilliant astronomer who transformed modern science, symbolically uniting the exploration of the astronomical macrocosmos with the exploration of the microcosmos of superheavy atomic nuclei.

Copernicium-285 was obtained for the first time by bombarding a rotating plutonium-242 target with an extremely intense beam of calcium-48 ions accelerated at Dubna's U-400 cyclotron. The hot fusion reaction produced flerovium-289 atoms which, after a fraction of a second, spontaneously emitted a high-energy alpha particle, transmuting into copernicium-285. This nuclid survived almost half a minute before decaying again.

For years there was controversy among laboratories about whether the elements discovered in Dubna through fusion with calcium-48 were genuine or experimental artifacts. The chemical and decay tests of copernicium-283 served as an indisputable link: by confirming copernicium's radioactive signature in independent laboratories in Germany and Switzerland, the entire series of superheavy element discoveries from the island of stability coast was formally validated.

In 2007, a Swiss-Russian team in Dubna transported copernicium-283 atoms with helium gas through a channel lined with gold detectors cooled with liquid nitrogen to −180 °C. While mercury adsorbed immediately at room temperature at the channel entrance, copernicium advanced to the coldest zones before weakly physisorbing, experimentally demonstrating its extreme chemical volatility predicted by relativistic quantum theory.

No sample of copernicium has been gathered to directly observe its physical state at room temperature. Theoretical calculations and some single-atom experiments suggest it could be relatively volatile and differ from a conventional metal. Therefore, stating with certainty whether a sample would be solid, liquid or gaseous goes beyond what is experimentally confirmed.

In alkaline earth metals and group 12, two s electrons are usually easily given up to form ionic or metallic bonds. However, in copernicium the ionization energy of the 7s electrons skyrockets due to relativistic contraction, while the 6d orbitals are full and screened. This symmetric closed architecture prevents efficient molecular orbital overlap, making copernicium chemically similar to a group 18 noble gas.