Copernicium · element 112
Honours the astronomer who moved the Earth, and behaves like a mercury that is slightly reluctant to stick
Key facts
Copernicium is named after Nicolaus Copernicus, the Polish astronomer who in the sixteenth century put the Sun rather than the Earth at the centre of the solar system. The name became official on 19 February 2010, the 537th anniversary of his birth. The discoverers wanted to honour a scientist who changed how people saw the world, and to look beyond the usual roll call of nuclear physicists.
Element 112 sits at the bottom of group 12, under zinc, cadmium and mercury. Mercury is the only metal that is liquid at room temperature, and some theorists predicted that copernicium might go further and be a gas. The experiments done so far suggest it is a metal after all, but an unusually aloof one.
Where it is found
Copernicium does not exist in nature. Its longest-lived isotope survives for around thirty seconds, so nothing made in a star could have reached the Earth. Every atom studied has been made artificially, and the total is of the order of a hundred, most appearing as decay products rather than being made directly.
The GSI discovery reaction fired zinc-70 at lead-208 to make copernicium-277, a cold fusion route with an extremely low yield: one atom in 1996 and one more in 2000. The isotopes chemists actually use, copernicium-283 and 285, come from another direction. When flerovium is made at Dubna from plutonium and calcium-48, it emits an alpha particle and becomes copernicium, which can be swept away and studied for the half-minute it survives.
How it was discovered
Sigurd Hofmann's team at GSI in Darmstadt detected a single atom of copernicium-277 on 9 February 1996 and traced its alpha decays down through darmstadtium, hassium and seaborgium to known isotopes. A second experiment in 2000 produced only one more atom. Confirmation came from RIKEN in Japan in 2004 and from the flerovium decay chains observed at Dubna, and IUPAC formally credited GSI in 2009.
The team proposed copernicium with the symbol Cp. That caused a problem. Cp had once been the symbol for cassiopeium, an old name for lutetium, and organic chemists use it as shorthand for the cyclopentadienyl group. IUPAC asked for a change, and the symbol became Cn. The name itself was approved in 2010, ending a fourteen-year wait between the first atom and the final name.
What we use it for
Copernicium has no uses. Its scientific importance is that it is the heaviest element whose chemical behaviour has been measured in a reasonably convincing way, and the results settled a genuine argument.
Zinc, cadmium and mercury have filled d and s shells, which makes them relatively unreactive and low-melting. In copernicium, relativity pulls the 7s electrons in so tightly that some calculations predicted noble-gas behaviour. In 2007 a team at Dubna working with the Paul Scherrer Institute let a few atoms of copernicium-283 drift along a gold-lined channel with a temperature gradient. They stuck to the gold at a lower temperature than mercury does, but far higher than radon: copernicium is a metal that bonds weakly to gold, and is even more volatile than mercury.
Reading the numbers
The atomic mass of 285 is the most stable known isotope. The predicted density of about 14 grams per cubic centimetre is close to mercury's 13.5, supporting a mercury-like metal. The boiling point shown, about 357 kelvin or 84 degrees Celsius, is a prediction, not a measurement, and some calculations go further and suggest copernicium could be a gas at room temperature. Nothing has been measured directly, and the melting point and electronegativity are unknown.
The configuration [Rn] 5f14 6d10 7s2 is a closed shell in both d and s, which is what group 12 requires. Predicted oxidation states are +2, like mercury, and possibly +4, which mercury does not readily reach. The adsorption experiments are the one place where prediction met reality, and reality landed between the two extremes. Copernicium is a metal, but only just.
Safety and the environment
Copernicium is radioactive in every form, with half-lives from under a millisecond to around thirty seconds. It cannot be stored, released or accumulated. The hundred or so atoms ever produced were created inside shielded accelerators and detected through their decay. There is no copernicium in the environment and no possible route for public exposure.
Did you know?
- The name copernicium was made official on 19 February 2010, the anniversary of Copernicus's birth in 1473.
- The original symbol Cp was rejected because chemists already used it for the cyclopentadienyl group and it had once stood for cassiopeium, an old name for lutetium.
- Only one atom was detected in the 1996 discovery experiment and one more when it was repeated in 2000.
- Experiments in 2007 showed copernicium atoms stick to gold, proving it is a metal, though it is even more volatile than mercury.
- Copernicus's great work, On the Revolutions of the Heavenly Spheres, was published in 1543, the year he died.
More in the superheavy elements
The nearest neighbours of copernicium in the family, by atomic number.
See all 15 superheavy elements on one page, or browse all 118 elements. Also listed under the transition metals.
Frequently asked questions
Who is copernicium named after?
Nicolaus Copernicus, the Polish astronomer who proposed in the sixteenth century that the Earth orbits the Sun. The name was chosen by the GSI team in Darmstadt and approved by IUPAC in 2010.
Is copernicium a gas?
Possibly. Some predictions suggest it could be a gas or a very volatile liquid at room temperature because relativistic effects make its electrons unusually tightly bound. Experiments show it does bond weakly to gold like a metal, but its actual boiling point has never been measured.
Why is the symbol Cn and not Cp?
The discoverers first proposed Cp, but that symbol was already used in organic chemistry for the cyclopentadienyl group and had historically stood for cassiopeium, an old name for lutetium. IUPAC asked for a different symbol and Cn was adopted.
What is the half-life of copernicium?
The discovery isotope, copernicium-277, lasted under a millisecond. The most stable known isotope, copernicium-285, has a half-life of around thirty seconds.
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Written by Anthony. Updated September 2026. Numerical data from Periodic-Table-JSON (CC BY-SA), cross-checked against the Copernicium reference article. Spotted an error? Tell us.