Isotopes of hassium

Hassium (₁₀₈Hs) 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 ²⁶⁵Hs in 1984. There are 13 known isotopes from ²⁶³Hs to ²⁷⁷Hs and up to six isomers. The most stable known isotope is ²⁷¹Hs, with a half-life of about 46 seconds, though this assignment is not definite due to uncertainty arising from a low number of measurements. The isotopes ²⁶⁹Hs and ²⁷⁰Hs respectively have half-lives of about 12 seconds and 7.6 seconds. It is also possible that the isomer ^277mHs is more stable than these, with a reported half-life 130±100 seconds, but only one event of decay of this isotope has been registered as of 2016.^[2][3]