ELEMENTLE

Element 112 · Transition Metal

Copernicium

Period 7 · Group 12

Copernicium is a chemical element with symbol Cn and atomic number 112. It is an extremely radioactive synthetic element that can only be created in a laboratory. The most stable known isotope, copernicium-285, has a half-life of approximately 29 seconds, but it is possible that this copernicium isotope may have a nuclear isomer with a longer half-life, 8.9 min.

Three reasons Copernicium stands out

  1. 1

    Named after famous astronomer who developed the heliocentric theory.

  2. 2

    It is predicted to behave more like a noble gas than a metal due to extreme relativistic effects on its electrons.

  3. 3

    It was officially named in 2010 on the 537th anniversary of the birth of the scientist it was named after.

A volatile metal at the edge of expectation

Copernicium is named for Nicolaus Copernicus and occupies the position below mercury. Its electrons move so rapidly that relativistic effects strongly reshape its predicted chemistry. Experiments suggest surprising volatility, fueling debate over how metallic a bulk sample would be—if one could exist.

Copernicium at a glance
Atomic number / protons112
SymbolCn
Family (Elementle)Transition Metal
Classification (PubChem)Transition metal
Period7
Group12
Atomic mass (u)286.179
Standard stateBulk state not experimentally established
Electron configuration[Rn]7s2 5f14 6d10 (predicted)
Reported oxidation states2, 1, 0
Electronegativity (Pauling)Not available
Atomic radius (pm)Not available
First ionization energy (eV)Not available
Electron affinity (eV)Not available
Density (g/cm³)Not available
Melting pointNot available
Boiling pointNot available
Discovery (PubChem)1996

Values are reference data, not a specification for every temperature, pressure, or allotrope. Unknown properties are left unavailable. Superheavy-element predictions remain uncertain.

Sources & further reading

PubChem: Copernicium · Copernicium on Wikipedia

The introduction and original editorial story are adapted from Wikipedia contributors via Periodic-Table-JSON. Element descriptions and their adaptations are available under CC BY-SA 3.0. Numerical attributes use the PubChem periodic-table dataset, retrieved September 22, 2026.