“Ytterbite”, Ytterby, Sweden Unknown heavy mineral, Bastnäs, Sweden (Carl Axel Arrhenius, 1757‐1824) (Axel Fredrik Cronstedt, 1722‐1765) late 1780s 1751 Renamed cerite and analyzed to contain a new “earth”, named ceria Analyzed to contain a new “earth” (Wilhelm Hisinger, 1766‐1852 & (Johan Gadolin, 1760‐1852) Renamed gadolinite Jöns Jacob Berzelius , 1779‐1848; 1789‐1794 (Martin Heinrich Klaproth, 1743‐1817) Martin Heinrich Klaproth, 1743‐1817) 1800 1803 Confirmed and named yttria (Anders Gustaf Ekeberg, 1767‐1813) 1797 Metallic yttrium (Yt, then Y) isolated Lanthanum (La) and didymium (Di) identified (Friedrich Wöhler, 1800‐1882) “Uranotantal”, Blyumovskaya pit, as components of ceria (Carl Gustaf Mosander, 1797‐1858) 1828 Ilmeny Mts., Russia 1839‐1841 (Gustav Rose, 1798‐1873) 1840 Yttria = yttria + erbia + terbia (Carl Gustaf Mosander, 1797‐1858) 1843 Renamed samarskite (Heinrich Rose, 1795‐1864) Metallic cerium (Ce) isolated Renamed terbia Renamed erbia 1847 (William F. Hillebrand, 1853‐1925 late 1870s 1860s & Thomas H. Norton, 1851‐1941) 1875 Erbia = erbia + ytterbia (Jean C.G. de Marignac, 1817‐1894) Gadolinia idenitified in Didymium = neodymium (Nd) + praseodymium (Pr) (Carl Auer von Welsbach, 1872‐1938) Dysprosium (Dy) identified in “holmia” Erbia = erbia + holmia + thulia 1878 didymium and yttria samples (Jean C.G. de Marignac, 1817‐1894; 1885 (Paul É.L. de Boisbaudran, 1838‐1912) (Per Teodor Cleve, 1840‐1905) Ytterbia = neoytterbia + lutecia Europium is isolated from samaria Paul É.L. de Boisbaudran, 1838‐1912) 1878 1878‐1879 (Georges Urbain, 1872‐1938) (Eugène‐Anatole Demarçay, 1852‐1904) 1880‐1886 1907 1901 Metallic neodymium isolated Metallic thulium (Tm) isolated Ytterbia = aldebaranium + cassiopeum 1925 (Charles James, 1880‐1928) (Carl Auer von Welsbach, 1872‐1938) Metallic praseodymium isolated 1911 1908 1931 Metallic erbium (Er) isolated Promethium Fission products of uranium fuel irradiated ina (W. Klemm & H.Bommer) (Jacob A. Marinsky, 1918‐2005; graphite reactor, Oak Ridge (USA) 1934 Metallic dysprosium (Dy), ytterbium Lawrence E. Glendenin, 1918‐2008; (Yb) and lutetium (Lu) isolated Charles D. Coryell, 1912‐1971) (Frank Harold Spedding, 1902‐1984) 1945 (announced in 1947) early 1950s

Sources: Aldersley‐Williams H (2011) Periodic Tales: A Cultural History of the Elements, from Arsenic to Zinc. Ecco, 448 pp; Emsley J (2003) Nature’s Building Blocks: An A‐Z Guide to the Elements. Oxford University Press, Oxford, 560 pp; Kean S (2010) The Disappearing Spoon and Other Tales of Madness, Love, and the History of the World from the Periodic Table of the Elements. Little, Brown & Co., UK, 400 pp