( C) Percentage of chemical space spanned by some elements. ( B) Absolute (left axis ) and cumulative values (right axis ) of new substances and combinations. Elements in black were considered in this study. ( A) Current SCE depicting elements known by 1869 (black), undiscovered elements (gray), and mixtures that were thought to be elements (red) ( SI Appendix). Chemical elements, growth, and diversity of the chemical space up to 1869. Although our approach is computational rather than historical, we hope it can complement other tools of the history of chemistry.įig. By analyzing these systems, from Dalton up to Mendeleev, Gmelin’s atomic weights of 1843 produce systems remarkably similar to that of 1869, a similarity that was reinforced by the atomic weights on the years to come. To account for the role of nineteenth century atomic weights upon the system, we introduced an algorithm to adjust the space according to different sets of weights, which allowed for estimating the resulting periodic systems of chemists using one or the other weights. Emphasis of the space upon organic chemicals after 1830 prompted the recognition of relationships among elements participating in the organic turn and obscured some of the relationships among transition metals. Chemical events in 1826 and in the 1840s were driven by the discovery of new forms of combination standing the test of time. Hence, the system was already encoded in the space for about two and half decades before its formulation. Here, we show by analyzing the space between 18 that after an unstable period culminating around 1826, chemical space led the system to converge to a backbone structure clearly recognizable in the 1840s. Little is known, however, about how the expansion of the space contributed to the emergence of the system-formulated in the 1860s. The periodic system, which intertwines order and similarity among chemical elements, arose from knowledge about substances constituting the chemical space.
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