Copernicium is a synthetic, highly radioactive transactinide element in group 12, named to honor Nicolaus Copernicus. Only a few atoms have ever been produced; bulk properties are largely unknown.
Copernicium (Cn) is a synthetic transactinide with atomic number 112. It lies in Group 12 (with Zn, Cd, Hg) and period 7. It does not occur naturally and is created atom-by-atom in particle accelerators.
Copernicium was first synthesized by fusing a heavy lead target with zinc ions. A classic discovery route is:
\(^{208}\mathrm{Pb}(^{70}\mathrm{Zn},\,n)\,^{277}\mathrm{Cn}\)
The hot compound nucleus cools by evaporating a neutron \((n)\) and the newborn Cn atoms are transported within milliseconds to detectors.
Fresh Cn atoms recoil from the target into a separator and implant into position-sensitive detectors. Identification uses time-correlated decay chains—mostly \(\alpha\)-decay and sometimes spontaneous fission—with characteristic energies and lifetimes:
\(^{A}_{112}\mathrm{Cn} \;\xrightarrow{\alpha}\; ^{A-4}_{110}\mathrm{Ds} + \alpha \;\to\; \cdots\)
Several short-lived isotopes (mass numbers near ~277–285) have been reported. Some isotopes live for only milliseconds, while others reach the seconds to tens-of-seconds range before alpha-decaying or fissioning, enabling limited chemistry experiments.
By analogy with mercury (Hg), +2 is the most likely condensed-phase oxidation state for Cn; +1 and 0 (elemental) are also discussed in theory. However, direct aqueous chemistry is not yet established because of extreme scarcity and short half-lives.
Relativistic effects strongly contract and stabilize the 7s electrons and influence 6d orbitals, making Cn predicted to be very weakly reactive—perhaps even more volatile and inert than Hg. Single-atom gas-phase adsorption on gold suggests very low adsorption enthalpy, consistent with noble-metal-like or quasi-noble-gas behavior.
A commonly cited ground-state configuration is [Rn] 5f14 6d10 7s2. Strong relativistic stabilization of 7s and changes in 6d levels help explain its expected low reactivity and high volatility.
Theoretically, halides (e.g., CnF2, CnCl2) and oxohalides might exist under extreme conditions. In practice, single-atom thermochromatography indicates that elemental Cn is already quite volatile, and definitive series of stable condensed-phase compounds have not been established.
Only a few atoms are produced per experiment and they decay quickly. This prevents preparing macroscopic samples to measure density, melting point, or crystal structure. Most property estimates come from theory and atom-at-a-time gas-phase chemistry.
Production (stylized):
\(^{208}\mathrm{Pb}(^{70}\mathrm{Zn},\,n)\,^{277}\mathrm{Cn}\)
Generic decay step:
\(^{281}\mathrm{Cn} \;\xrightarrow{\alpha}\; ^{277}\mathrm{Ds} + \alpha\)