Resumo

BERNAL, Juan Pablo  e  RAILSBACK, L. Bruce. An introduction to the Periodic Table of the Elements and their ions for the Earth Sciences. Rev. mex. cienc. geol [online]. 2008, vol.25, n.2, pp.236-246. ISSN 2007-2902.

This paper presents the basic principles behind "An Earth Scientist's Periodic Table of the Elements and Their Ions", originally published in Railsback, L.B., 2003, An Earth scientist's periodic table of the elements and their ions, Geology, 31(9): 737-740. In contrast to Mendelejeff's periodic table, -where all elements are classified according to their ground state (or oxidation state = 0), the Periodic Table of the Elements and Their Ions, classifies elements and ions according to their natural oxidation state. Consequently, some elements are displayed in several positions within the table, and some others have been relocated. The classification of the ions according to their oxidation state allows the visualization of trends based upon intrinsic characteristics of each ion (such as polarizability and ionic potential) that evidence the biogeochemical behavior of the elements and their ions. Many of those trends were only semi-empirically inferred until now. Reaction paths for different ions are deducted from their polarizability, whereas the ionic potential allows to infer the behavior of the ions under diverse geochemical differentiation processes. It is shown that the interaction of different cations with the oxide ion (O^2-) plays a pivotal role in most processes of geochemical differentiation, such as aqueous geochemistry, weathering, igneous petrogenesis, among others. Because of the wide range of applications, The Periodic Table of The Elements and Their Ions is a valuable tool for the earth scientist.

Palavras-chave : Elements; ions; periodic table; polarizability; ionic potential; classification.