Darmstadtium (Ds). Diagram of the nuclear composition and electron configuration of an atom of darmstadtium-281 (atomic number: 110), the most stable isotope of this radioactive element. The nucleus consists of 110 protons (red) and 171 neutrons (yellow). 110 electrons (white) bind to the nucleus, successively occupying available electron shells (rings). Named for where it was first synthesised in 1994, it is a transactinide of unknown properties in group 10, period 7, and the d-block of the periodic table. Darmstadtium-281 has two forms (nuclear isomers), with half-lives of 11 seconds and 3.7 minutes.