Scandium is the most advanced transition metal with atomic number of only 21. However, as far as discovery is concerned, scandium is later than its neighbors on the periodic table. Even in rare earths, scandium was not discovered earlier. The reason for its late discovery is simple. The content of scandium in the crust is only, which is equivalent to 5g per ton of crustal material, much lower than other light elements. In addition, it is very difficult to separate rare earth elements, so it is not easy to find scandium from mixed mineral deposits. However, although it has not been found, the existence of this element has been predicted. In the first edition of the periodic table of elements given by Mendeleev in 1869, a vacancy with atomic weight of 45 was left behind calcium. Later, Mendeleev temporarily named the element after calcium Eka Boron, and gave some physical and chemical properties of this element.
Discovery History
In the late 19th century, the study of rare earth elements became a hot trend. One year before the discovery of scandium, de Marignac of Switzerland obtained a white oxide different from erbium earth from rose red erbium earth by partially dissolving nitrate. He named this oxide ytterbium earth, which is the sixth place in the discovery of rare earth elements. L.F. Nilson (1840~1899) of Uppsala University in Sweden purified erbium earth according to Malinak's method, and accurately measured the atomic weight of erbium and ytterbium (because he was focusing on accurately measuring the physical and chemical constants of rare earth elements at this time to verify the periodic law of elements). After 13 times of partial decomposition, 3.5g pure ytterbium earth was obtained. But then something strange happened. Malinack gave the atomic weight of ytterbium as 172.5, while Nielsen got only 167.46. Nielsen was keenly aware of what light elements might be inside. Then he continued to process the obtained ytterbium soil with the same process. Finally, when only one tenth of the sample was left, the measured atomic weight dropped to 134.75; At the same time, some new absorption lines were found in the spectra. Nelson named scandium Scandium after his native Scandinavia. In 1879, he officially published his research results. In his paper, he also mentioned many chemical properties of scandium salts and scandium soils. However, in this paper, he has not been able to give the precise atomic weight of scandium, nor is he sure about the position of scandium in the element cycle.
Nelson's friend, P.T. Cleve (1840-1905), who also teaches at Uppsala University, also did this work together. Starting from erbium earth, he eliminated erbium earth as a large number of components. After separating ytterbium earth and scandium earth, he found holmium and thulium, two new rare earth elements, from the residue. As a by-product, he purified scandium earth and further understood the physical and chemical properties of scandium. In this way, Clive finally picked up the drifting bottle released by Mendeleev after sleeping for ten years.
Scandium is the "boron like" element predicted by Mendeleev. Their discovery once again proved the correctness of the periodic law of elements and Mendeleev's foresight.
Scandium metal was only produced by electrolytic melted scandium chloride in 1937.
