CLASSIFICATION OF LANTANIDES ON THE BASIS OF DISCRIMINANT AND CLUSTERANALYSES

Lanthanides are classified with regard to the following properties of elements: nuclear charge, ionization potentials, structure of electron shell, and orbital radius. Discriminant analysis showed that the conv entional recognition of tetrads (according to chemical properties) in lanthanide series can be explained only by tendencies in variation of the third ionization potential of these elements. The total classifica tion of these elements is complicated and requires consideration of mu ltidimensional space of their properties. This space is mapped onto a plain as a dendrogram obtained by cluster analysis. This dendrogram pr esents the order of lanthanide integration into subgroups according to separation between them in the multidimensional space, i.e., classifi cation with simultaneous consideration of all Properties of elements. Lanthanum, gadolinium, and lutetium significantly differ from other el ements of the series and from each other. The difference in properties between the first and the second half of the series is noticeable; pa irs of elements closest to each other in properties are revealed: sama rium and europium in the first half of the series and thulium and ytte rbium in the second part.