Radioactive elements

Tc Technetium Transition metal · Z 43 · 98 u The first element made by humans rather than found — and the lightest with no stable isotope at all. Pm Promethium Lanthanide · Z 61 · 145 u The only lanthanide with no stable isotope — it decayed away and had to be made in a reactor. Po Polonium Post-transition metal · Z 84 · 209 u Intensely radioactive: a gram of polonium-210 emits enough alpha particles to glow blue and self-heat to 500 degrees C. At Astatine Metalloid · Z 85 · 210 u The rarest naturally occurring element on Earth — perhaps 25 grams exist in the entire crust at any moment. Rn Radon Noble gas · Z 86 · 222 u A radioactive noble gas that seeps out of granite and is the second leading cause of lung cancer. Fr Francium Alkali metal · Z 87 · 223 u The second rarest natural element, and the most electropositive — but no one has ever seen a visible sample. Ra Radium Alkaline earth metal · Z 88 · 226 u The element that glowed in the dark on watch dials, and killed the women who painted them. Ac Actinium Actinide · Z 89 · 227 u Intensely radioactive and 150 times more so than radium — actinium glows pale blue in the dark. Th Thorium Actinide · Z 90 · 232.038 u Three times more abundant than uranium and a potential reactor fuel that cannot easily be weaponised. Pa Protactinium Actinide · Z 91 · 231.036 u One of the rarest and most expensive natural elements — extracting 125 g once cost half a million dollars. U Uranium Actinide · Z 92 · 238.029 u The heaviest primordial element, and the one that split the twentieth century in two. Np Neptunium Actinide · Z 93 · 237 u The first transuranic element, made by bombarding uranium with neutrons in 1940. Pu Plutonium Actinide · Z 94 · 244 u The element that made the atomic age possible and powers spacecraft beyond the Sun's reach. Am Americium Actinide · Z 95 · 243 u The element quietly sitting in millions of smoke detectors worldwide. Cm Curium Actinide · Z 96 · 247 u Named for the Curies, and the isotope that has analysed the soil of Mars. Bk Berkelium Actinide · Z 97 · 247 u Made in nanogram quantities and used mainly as a target for creating even heavier elements. Cf Californium Actinide · Z 98 · 251 u A neutron source strong enough to be used in oil-well logging and cancer treatment. Es Einsteinium Actinide · Z 99 · 252 u Discovered in the fallout of the first hydrogen bomb test, in samples flown through the cloud. Fm Fermium Actinide · Z 100 · 257 u The heaviest element that can be made in weighable amounts by neutron bombardment. Md Mendelevium Actinide · Z 101 · 258 u The first element produced and identified one atom at a time. No Nobelium Actinide · Z 102 · 259 u The subject of a decade-long discovery dispute between Swedish, American and Soviet teams. Lr Lawrencium Actinide · Z 103 · 262 u The last actinide, with an electron configuration that broke the expected pattern. Rf Rutherfordium Transition metal · Z 104 · 267 u The first transactinide — and chemically a heavier cousin of hafnium, not an actinide at all. Db Dubnium Transition metal · Z 105 · 268 u Named after Dubna, the Russian town where much of superheavy chemistry was pioneered. Sg Seaborgium Transition metal · Z 106 · 271 u Named for Glenn Seaborg while he was still alive — a first for the periodic table. Bh Bohrium Transition metal · Z 107 · 272 u A superheavy element whose chemistry, tested one atom at a time, behaves as predicted for group 7. Hs Hassium Transition metal · Z 108 · 270 u The heaviest element whose chemical properties have been experimentally confirmed. Mt Meitnerium Transition metal · Z 109 · 276 u Named for Lise Meitner, who explained nuclear fission but was left off the Nobel Prize. Ds Darmstadtium Transition metal · Z 110 · 281 u Created at Darmstadt in 1994 by fusing nickel and lead nuclei. Rg Roentgenium Transition metal · Z 111 · 280 u Named for the discoverer of X-rays, and predicted to be chemically like gold. Cn Copernicium Transition metal · Z 112 · 285 u Predicted to be a volatile liquid — a metal that behaves almost like a noble gas. Nh Nihonium Post-transition metal · Z 113 · 284 u The first element discovered and named by an Asian research team. Fl Flerovium Post-transition metal · Z 114 · 289 u Predicted to sit in an "island of stability" where superheavy nuclei live far longer. Mc Moscovium Post-transition metal · Z 115 · 288 u Its decay chain provided crucial confirming evidence for the discovery of nihonium. Lv Livermorium Post-transition metal · Z 116 · 293 u Made by fusing calcium-48 with curium-248, and decays within milliseconds. Ts Tennessine Halogen · Z 117 · 294 u The second-to-last gap in the seventh period, filled in 2010 with a berkelium target. Og Oganesson Noble gas · Z 118 · 294 u The heaviest element ever made, and the only one named after a living person at the time.