Scandium - eka-Boron

Lars Fredrik Nikon was professor of chemistry in Uppsala and cooperated with Per. T. Cleve over rare earth metals. In 1879 he attempted to verify Marignac s ytterbium and isolated erbium from gadolinite. He used the method described by Marignac and verified the existence of ytterbium within two months. 

Having obtained 10 kg of euxenite from Norway, Nilson could prepare oxides of both ytterbium and scandium in quantities large enough for atomic weight determinations. His values were 173 for ytterbium and 44 for scandium. Modem atomic weights are 173.04 and 44.96 respectively. 

The oxide of scandium was white and its solutions were colorless. In the spectroscope around 30 distinct Hnes were visible, easily separated from the Hnes of ytterbium and other metals. 

According to Szabadvary and Evans, pp 55-66 in ref. [17.9] the importance of Nil-son s discovery of scandium surpassed an ordinary element discovery, as it verified the occurrence of the element to which Mendelejev had given the name eka-boron. 

In Table 17.7 Mendelejev s predictions for eka-boron are compared with Nilson s and Cleve s findings after the discovery of scandium. 

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The predictive power of Mendeleev s periodic table was demonstrated again when scandium (eka-boron) was discovered in 1879 and germanium (eka-silicon) in 1886. Both elements had properties remarkably like those predicted by Mendeleev. These early successes won acceptance for the organizational and predictive power of the periodic table. 

On what grounds did Mendeleev foretell the existence of scandium (eka-boron) Explain the principles according to which he described its properties before the body had been actually obtained. (Note his use of body rather than element) ... 

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