High Quality Content by WIKIPEDIA articles! Darmstadtium (Ds) is an artificial element, and thus a standard atomic mass cannot be given. Like all artificial elements, it has no stable isotopes. The first isotope to be synthesized was 269Ds in 1994. There are 7 or 8 known radioisotopes from 267Ds (or 269Ds) to 281Ds (with many gaps) and 2 or 3 known isomers. The longest-lived isotope is 281Ds with a half-life of 9.6 seconds.