The lanthanides: Neither earths nor rare

Abstract

The periodic table of elements contains the fundamental basis of past, present, and future knowledge of Chemistry. However, additional and complementary models are still proposed to try to satisfy the unique physical and chemical properties of those that do not conform to it. Some of these questions will surely have explanations based on quantum approaches, obviously unknown in the time of the original proposal. In the periodic table, there are two typical relevant situations related to rare lands and actinides, involving about 30 elements. These are displayed as annexes outside the intended order and having group characteristics, they are organized as periods. Despite discussions regarding the relocation of these elements, which is not an irrelevant academic exercise, rare earths are now valuable materials with multiple applications and they have a fundamental role in economic balance and global politics. This article presents several aspects related to their position in the periodic table, as well as the structural and electronic properties of their favorable and unusual behaviors, their applications, and the international context for global hegemony founded on this type of elements.