Periodic Table for Earth Sciences

On the occasion of the 150th anniversary of the discovery of the periodic table, the ICGC has produced the Catalan version of the periodic table.

On the occasion of the 150th anniversary of the discovery of the periodic table, the United Nations General Assembly and UNESCO proclaimed the year 2019 as the “International Year of the Periodic Table of Chemical Elements (IYPT2019)”. In support of this anniversary, the ICGC has produced the Catalan version of the Railsback periodic table (2003).

The Periodic Table of Chemical Elements, originally conceived by Dmitri Mendeleev in 1869, is one of the most significant achievements in science, capturing the essence not only of chemistry, but also of physics, biology and geology. On the occasion of the 150th anniversary of the discovery of the periodic table, the United Nations General Assembly and UNESCO have proclaimed the year 2019 as the “International Year of the Periodic Table of Chemical Elements”.

In support of this anniversary (IYPT2019), the Cartographic and Geological Institute of Catalonia, as a public entity of the Generalitat de Catalunya whose purpose is to carry out actions related to knowledge, prospection and information about the soil and subsoil, has produced the Catalan version of the periodic table An Earth Scientist's Periodic Table of the Elements and their Ions prepared by Bruce Railsback (2003, Geology 31: 737-740).

Taula Periòdica dels Elements i dels seus Ions per a les Ciències de la Terra(36.35 MB)

The publication of the “Periodic Table of Elements and Their Ions for Earth Sciences” responds to the objective of promoting the standardization of geological language in Catalan and of disseminating a synthesis document that can serve as a reference framework for the development of future geochemical work and the assessment of environmental quality.

The use of the conventional periodic table in the field of geochemistry is often limited by the fact that much of the matter that makes up the Earth is not found in elemental form. Most of the atoms that make up minerals and other natural terrestrial materials have a charge. For example, in the case of silicon, it is well known that, in nature, it is mostly found as Si4+ forming minerals from the silicate group.

To represent the chemistry of the Earth in a synthetic way, a periodic table is needed that, in addition to the elemental forms, specifies the ions that are found in natural conditions. In this context, Bruce Railsback published “An Earth Scientist’s Periodic Table of the Elements and their Ions” in 2003, a new periodic table adapted to Earth chemistry.

The “Periodic Table of the Elements and their Ions for Earth Sciences” provides a useful framework for understanding the distribution of chemical elements and the functioning of Earth’s geochemical processes. It shows trends, patterns, and interrelationships characteristic of mineralogy, soil and sediment geochemistry, endogenous petrology, hydrogeochemistry, isotopic geochemistry, and nutrient chemistry.

Organization of the periodic table

The organization in the table of the different forms present on Earth is fundamentally based on the ionic charge, the ionic potential (the quotient between the ionic charge and the ionic radius) and the number of electrons in the valence layer (which defines the degree of hardness). The table is divided into five large groups of chemical forms: the noble gases, the hard cations (in which all the electrons have been removed from the valence layer), the intermediate and soft cations (in which the valence layer retains some or most of the electrons), the native forms (uncharged except for the noble gases), and the anions (the negative ions, which capture electrons). In this distribution are superimposed isolines referring to the ionic potential that define sets of ions with similar geochemical behaviors.

The grouping of the cations according to their degree of hardness makes sense in that the hard cations tend to form strong bonds with O^2– but not with S^2–, while the soft ones tend to bond especially with S^2– and other heavier anions such as Br^– and I^–. In geological terms, this differentiation is important given that oxygen, in the form O^2–, is the most abundant element in the Earth's mantle and crust and, consequently, many of the geochemical processes that take place are conditioned by this fact. On the other hand, sulfur is also an important element since there is a good number of elements, the chalcophiles, which tend to bind together to form sulfides of metallic types such as sphalerite (ZnS), stibin (Sb₂S₃), cinnabar (HgS) or galena (PbS).

One of the most remarkable results of ordering the elements according to the load is that many of them appear several times. As a result of this system, most elements are represented twice (for example, uranium appears as U⁴⁺ and U⁶⁺), several are represented three times (for example, iron appears as Fe, Fe²⁺ and Fe³⁺) and others more than three times (for example, sulfur appears as S^2–, S, S⁴⁺ and S⁶⁺).

For each element, the table shows the atomic number, the atomic mass, the isotopes present in nature and the radioactive decay chains. In addition, for each form, its radius (ionic or atomic, depending on its charge) and its associated number are specified. For example, in the case of S⁶⁺ it is specified "sulphur as sulfate SO₄^2-", S⁴⁺ "sulfur as sulphite SO₃^2-", S^2- "sulfur as sulphur" and native S simply "sulphur".

Element box

The size of the chemical symbols varies according to the element's abundance in the Earth's crust as a whole. The boxes associated with each ion or element in the periodic table include information regarding its abundance and distribution in the Earth's various geochemical compartments. Using a highly original symbol system, the table indicates the tendency of ions to concentrate in the core, mantle, igneous rocks, ocean floors, seawater, river water, sediments, soils, the atmosphere, and, finally, the different types of nutrients necessary for life. These tendencies are the product of a large number of thermodynamic processes that, more or less directly, are related to mineral balance. In this sense, the periodic table identifies the forms (charged or neutral) that form some of the most important mineral groups present on Earth, such as sulfides, oxides, fluorides, and native minerals.

System of symbols that indicates the tendency of ions to concentrate in the core, mantle, igneous rocks, ocean floors, seawater, river waters, sediments, soils, the atmosphere and different types of nutrients

Finally, the periodic table includes, at the bottom, a series of diagrams of physical properties of minerals such as compressibility, melting point or solubility. These graphs show the relationships between these properties and the degree of hardness of the cations that form the minerals.

Compressibility modulus (Ks in GPa) of mineral oxides of hard cations

Geoinformation from the Cartographic and Geological Institute of Catalonia subject to a Creative Commons International Recognition 4.0 license
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Credits

Version 4.8e © 2012 L. Bruce Railsback, Department of Geology, University of Georgia, United States (author's page, http://railsback.org/PT.html). Catalan version by Miquel Vilà, ICGC (January 2019).
Version 4.7 was published in 2004 by the Geological Society of America in the Maps & Charts series (MCH092).
Version 4.6 of this table was published in Figure 1 of the article: Railsback, L.B., 2003: An Earth Scientist’s Periodic Table of the Elements and Their Ions. Geology v. 31 (9): 737-740.
The publication of Version 4.6 in Geology was funded by project DUE 02-03115 (National Science Foundation).