Isotopes of copernicium
Copernicium (112Cn) is a synthetic element, and thus a standard atomic weight cannot be given. Like all synthetic elements, it has no stable isotopes. The first isotope to be synthesized was 277Cn in 1996. There are 6 known radioisotopes (with one more unconfirmed); the longest-lived isotope is 285Cn with a half-life of 30 seconds.