The properties of the lanthanides arise from the order in which the electron shells of these elements are filled—the outermost (6s) has the same configuration for all of them, and a deeper (4f) shell is progressively filled with electrons as the atomic number increases from 57 towards 71. For many years, mixtures of more than one rare earth were considered to be single elements, such as neodymium and praseodymium being thought to be the single element didymium."The Elements", Theodore Gray, Black Dog & Leventhal, Chicago 2007: "Neodymium" and "Praseodymium" entries Ch 59 & 60, pp 138–43 Very small differences in solubility are used in solvent and ion-exchange purification methods for these elements, which require repeated application to obtain a purified metal. The diverse applications of refined metals and their compounds can be attributed to the subtle and pronounced variations in their electronic, electrical, optical, and magnetic properties.
the properties of the lanthanides arise from the order in which the electron shells of these elements are filled—the outermost (6s) has the same configuration for all of them and a deeper (4f) shell is progressively filled with electrons as the atomic number increases from 57 towards 71 for many years mixtures of more than one rare earth were considered to be single elements such as neodymium and praseodymium being thought to be the single element didymium"the elements" theodore gray black dog & leventhal chicago 2007 "neodymium" and "praseodymium" entries ch 59 & 60 pp 138–43 very small differences in solubility are used in solvent and ion-exchange purification methods for these elements which require repeated application to obtain a purified metal the diverse applications of refined metals and their compounds can be attributed to the subtle and pronounced variations in their electronic electrical optical and magnetic properties