Neo-ytterbium

Notice that Moseley had made a minor mistake in the atomic number determinations of both holmium and dysprosium. The atomic number of holmium is namely 67, and dysprosium has an atomic number of 66. It also appears that Moseley attached some credence to the investigation of Auer von Welsbach who had demonstrated the complexity of thulium in 1911 by splitting it into three components. Moseley had incorporated two of these components (Tml and Tmll) in his atomic number sequence. Moseley therefore ascribed Urbain s neo-ytterbium and lutetium too high an atomic number (in reality the atomic numbers of ytterbium and... 

Ytterbium (or neo-ytterbium) may be separated from lutecium by the fractional crystallization of the ammonium double oxalates in concentrated ammonium oxalate or by the fractional crystallization of the nitrates in nitric adds or by the difference in the volatility of their chlorides. 

Marignac showed that the rare earth erbia could be separated into two rare earths, ytterbia and another element later called holmium (figure 8.9). A year later, ytterbia was separated into two distinct elements named scandium and ytterbium. The next step was taken by Georges Urbain and Auer von Welsbach, who independently found that ytterbium itself could be separated into neo-ytterbium and lute-tium. It was only natural that these workers should suspect the possibility of discovering further new elements by repeated separations of the same minerals. 

Intensive work with ytterbium was going on in Paris at the same time. Georges Ur-hain reported to the Paris Academy of Science on 4 " November 1907 (44 days before Auer s second report to the Vienna Academy) that he had performed a total of 800 fractionations of ytterbium nitrates, prepared from the mineral xenotime. Now he announced that he had divided ytterbium into two elements, for which he proposed the names neo-ytterbium Ny and lutecium Lu. The former was Marignac s element, now purified, the latter named after an old name for Paris, Lutetia Parisorum. 

Lantha- num Cerium Praseo- dvnium Neo- dymium Prome- thium Samarium Europium Gadoli- nium Terbium Dyspro- sium Holmium Erbium Thulium Ytterbium... 

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