mendelevium

noun

1. (uncountable)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.”

   “Seven new elements were discovered with the 60-inch cyclotron: 85 (astatine), 93 (neptunium), 94 (plutonium), 96 (curium), 97 (berkelium), 98 (californium), and 101 (mendeleevium).”

   “In the expert hands of Enrico Fermi, beginning with 1934, neutron bombardment produced new atomic miracles. In 1940, Fermi created neptunium (Z = 93), the first artificial, 'trans-uranic', element. Others, also unstable, soon followed, among them fermium (Z = 100) and mendeleyevium (Z = 101).”

   “[Glenn Theodore] Seaborg would be the principal co-discoverer of ten elements on the periodic table: plutonium, americium, curium, berkelium, californium, einsteinium, fermium, mendelevium, nobelium, and element 106.”