Theoretical and Computational Chemistry

Are the chemical families still there? exploration of similarity among elements

Authors

  • Eugenio Llanos Ballestas Bioinformatics Group, Department of Computer Science, Universität Leipzig, Härtelstraße 16-18, 04107 Leipzig, Germany & Corporación SCIO, Calle 57b 50-50 bloque d22 of. 412, 111321 Bogotá, Colombia ,
  • Wilmer Leal Bioinformatics Group, Department of Computer Science, Universität Leipzig, Härtelstraße 16-18, 04107 Leipzig, Germany & Max Planck Institute for Mathematics in the Sciences, Inselstraße 22, 04103 Leipzig, Germany ,
  • Andrés Bernal Departamento de Ciencias Básicas, Universidad Jorge Tadeo Lozano, Carrera 4 22-61, 110311 Bogotá, Colombia ,
  • Jürgen Jost Max Planck Institute for Mathematics in the Sciences, Inselstraße 22, 04103 Leipzig, Germany & The Santa Fe Institute, 1399 Hyde Park Rd., Santa Fe, New Mexico 87501 ,
  • Peter F. Stadler Bioinformatics Group, Department of Computer Science, Universität Leipzig, Härtelstraße 16-18, 04107 Leipzig, Germany & Max Planck Institute for Mathematics in the Sciences, Inselstraße 22, 04103 Leipzig, Germany & Interdisciplinary Center for Bioinformatics, Universität Leipzig, Härtelstraße 16-18, 04107 Leipzig, Germany & Institute for Theoretical Chemistry, University of Vienna, Währingerstraße 17, 1090 Vienna, Austria & The Santa Fe Institute, 1399 Hyde Park Rd., Santa Fe, New Mexico 87501

Abstract

The Periodic Table (PT) is perhaps the most famous and widespread icon of chemistry. It orders chemical elements by their nuclear charge and groups them into families according to their similarity. Such arrangement was built using data about formulae of few compounds available in 19th century. Since then, the number of compounds has grown exponentially during the 20th and 21st centuries, and new types of compounds have been obtained that were unknown to pioneers, rising the question about the validity and generality of the PT. Can these patterns be extracted from current data or are they constrained to a particular chemical domain? To answer this question we conducted a Big Data exploration of chemical similarity using formulae of compounds reported since around 1800. We found that the similarities between elements of the same family are resilient to attacks and are ubiquitous along chemical contexts. We also found that PT groups approach true equivalence classes, being the most symmetrical and transitive on our data. These features point to an underlying structure in the PT ruling the similarity between elements, which agrees with its fundamental nature. Time analysis revealed that since around 1980 all similarity relations are waning by an increasing production of unique formulae on almost all elements, leading to a singularization of elements. Nonetheless, PT families tend to be more frequently found, showing they prevail over any other similarity pattern.

Content

Thumbnail image of are-chemical-families-still-there.pdf

Supplementary material

Thumbnail image of supp-inf-are-chemical-families-still-there.pdf
Supplementary Information
Several additional plots and tables