|Atomic mass||(277) amu|
Copernicium was first created on February 9, 1996, at the Gesellschaft für Schwerionenforschung (GSI) in Darmstadt, Germany. In 2000, the GSI successfully repeated the experiment to synthesise a further atom of Cn-277. This reaction was repeated in 2004 to synthesise two further atoms and confirm the decay data reported by the GSI team.
In 2009, the name copernicium with the element symbol Cp was proposed in honour of Nicolaus Copernicus.
Alternative spellings, namely "copernicum", "copernium", and "kopernikium" (Kp), were suggested. "Copernicium" was agreed upon in order to comply with current IUPAC rules, which allow only the suffix -ium for new elements. It was pointed out that the symbol Cp was previously associated with the name cassiopeium (cassiopium), now known as lutetium (Lu). Furthermore, the symbol Cp is also used in organometallic chemistry to denote the ligand cyclopentadiene. For this reason, the IUPAC disallowed the use of Cp as a future symbol, prompting the GSI team to put forward the symbol Cn as an alternative.
On February 19, 2010, the 537th anniversary of Copernicus' birth, IUPAC officially accepted the proposed name and symbol.