Copernicium (Cn)

Copernicium sits below mercury, and relativistic effects are expected to be so strong here that it may not behave like a metal at all: calculations suggest it could be a gas at room temperature, closer to a noble gas than to zinc or cadmium. Experiments passing single atoms over a gold surface found them sticking much more weakly than mercury does, which is consistent with the prediction but nowhere near conclusive on the handful of atoms available. It was named for Copernicus in 2010, on the anniversary of his birth.

Properties

Atomic number

112

Symbol

Cn

Mass number of most stable isotope

[285]

Category

Transition metal

Group

12

Period

7

Block

d-block

Electron configuration

[Rn] 7s² 5f¹⁴ 6d¹⁰

Electrons per shell

2, 8, 18, 32, 32, 18, 2

Oxidation states

+2, +1, 0

Discovered

1996 by Sigurd Hofmann and colleagues at GSI Darmstadt

Electron configuration

Full

1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s² 4d¹⁰ 5p⁶ 6s² 4f¹⁴ 5d¹⁰ 6p⁶ 7s² 5f¹⁴ 6d¹⁰

Noble gas shorthand

[Rn] 7s² 5f¹⁴ 6d¹⁰

Shells

K: 2 · L: 8 · M: 18 · N: 32 · O: 32 · P: 18 · Q: 2

What it is used for

• Research only; no application outside the laboratory

Hazards

• Intensely radioactive; exists only as individual atoms in an accelerator

Melting point, boiling point, density and electronegativity are omitted: no measurement is possible, and the predictions here are unusually uncertain because relativistic effects dominate. The mass given is the mass number of copernicium-285, the longest-lived at roughly 30 seconds.

Several physical properties are not listed for copernicium because no bulk sample has ever existed. Only a handful of atoms have been produced, often with half-lives measured in seconds, so published melting points and densities for elements in this range are calculations rather than measurements. They are omitted rather than presented as observed values.

Neighbours in the table

Group 12

Elements in the same group share their outer electron count, which is why they behave similarly in reactions. Copernicium sits in group 12 with zinc, cadmium, mercury.