The network theory: a new language for speaking about chemical elements relations through stoichiometric binary compounds

Abstract

Traditionally the study of chemical elements has been limited to well-known concepts like the periodic properties and chemical families. However, current information shows a new and rich language that allows us to observe relations in the elements that are not limited to their positions in the table. These relations are evident when reactions are represented through networks, as in the case of similar reactivity of organic compounds sharing functional groups. For the past two decades, it has been argued that network reactions may be considered the core of chemistry. This network, which constitutes the basic set of chemical knowledge, provides the basis for classification and delivers routes to obtain new and known substances. In order to provide an example, we constructed and analyzed a network of chemical elements from the formation of stoichiometric binary compounds, providing to the chemistry, a formal structure of extracting the chemical knowledge. Thus, we explored all possible presence of relationships among elements. Concepts like degree centrality and centralization, the relationships among metals, semimetal and nonmetal classes, blocks, and chemical families were analyzed. We observed that the network structure had a small core set of elements of high reactivity and also a peripheral set of elements of low reactivity. The classes, blocks and families show the following increasing order of reactivity: nonmetals > semimetals > metals; p > s > d > f; and families: boron, carbon, pnictogens, chalcogens, halogens, lanthanoids > other families. This example shows, from the network perspective, that the elements and their classifications exhibit properties such as the reactivity, order, and similarity.