mendelevium

noun

Etymology: From a modified version of Mendeleev + -ium (suffix forming names of metal elements), named in honour of the Russian chemist Dmitri Mendeleev (1834–1907) who formulated the periodic law and created an early version of the periodic table of elements. The word was proposed by a team from the University of California, Berkeley, comprising the team leader Stanley Gerald Thompson and members Gregory Robert Choppin, Albert Ghiorso, Bernard George Harvey, and Glenn T. Seaborg, who artificially synthesized the element in early 1955. (The same name was proposed, but rejected, for the earlier-discovered elements berkelium and erbium.)

1. A radioactive metallic transuranic chemical element (symbol Md) with atomic number 101, which is artificially produced in a particle accelerator.

   “Mendelevium, the heaviest and rarest form of matter known, has been produced in the University of California's cyclotron. Identity based on only 17 atoms of new element [subtitle]. […] Mendelevium is intensely radioactive, decaying by spontaneous fission. Its half-life is between a half hour and three hours. It has chemical properties similar to those of thulium, element 69, a rare earth.”

   “There's sulfur, californium, and fermium, berkelium, / And also mendelevium, einsteinium, nobelium, / And argon, krypton, neon, radon, xenon, zinc, and rhodium, / And chlorine, carbon, cobalt, copper, tungsten, tin, and sodium.”