AN EARTH SCIENTIST'S PERIODIC TABLE OF THE ELEMENTS AND THEIR IONS

Chemists' periodic tables of the elements are organized according to properties and characteristics of elements, rather than ions, and they show each element just once. Earth scientists, however, generally consider matter in naturally oxidized or reduced states. To solve this problem, the new Earth Scientist's Periodic Table of the Elements and Their Ions concentrates on charged species and, as a result, shows some elements twice or even three times because they ionize to multiple oxidation states. It also uses color-coded symbols to show patterns in relative abundances of elements in different geological materials and in the atmosphere. Patterns of coordination in aqueous solution are shown, as are isotopic data. Cations are divided into hard (oxygen-friendly) and soft (sulfur-friendly) groups.

Rearrangement of the table according to oxidation state shows how ionic potential controls the distribution of elements in igneous rocks, soils, groundwater, and seawater, and shows why some elements are critical nutrients in terrestrial or marine ecosystems. Cations that enter early-forming phases in igneous rocks are generally the same as those that are enriched in soils, because their intermediate ionic potential (z/r=4-9) allows strong cation-oxygen bonds. They form hydroxo-complexes in solution. Cations of low ionic potential form weaker bonds and only hydrate in solution. Cations of high ionic potential form strong cation-oxygen bonds, but they repel other cations of high ionic potential, and they form oxo-complexes in solution. Cations with low or high ionic potential thus are leached from soils and instead are abundant in seawater, and they can be limiting nutrients in terrestrial ecosystems. These groups occupy distinct swaths of the newly reorganized table.

The Earth Scientist's Periodic Table of the Elements and Their Ions organized according to oxidation state thus allows an integrated view of the geochemistry of the geosphere, hydrosphere, biosphere, and atmosphere. For more information and updates, see http://www.gly.uga.edu/railsback/PT.html.