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 seven known radioisotopes (with one more unconfirmed); the longest-lived isotope is ²⁸⁵Cn with a half-life of 28 seconds.