Published online by Cambridge University Press: 01 January 2022
Dmitrii Mendeleev’s periodic system is known for its predictive accuracy, but talk of its completeness is rarer. This is surprising because completeness (polnost’) was a quality that Mendeleev saw as important for a systematization of the chemical elements. Here, I explain how Mendeleev’s valuing of completeness influenced the development of his periodic system. After introducing five indicators of its completeness, I zoom into one in particular: Mendeleev’s inclusion of a schematic row of oxides. I then show how it guided Mendeleev’s predictions of indium and ekaboron, which suggests that the valuing of completeness was instrumental for making predictions.
I thank Hasok Chang, Anna Alexandrova, Oliver Marsh, Chris Campbell, Marion Kieffer, and the anonymous referees for their helpful feedback. This article benefited rom the discussions at the Association of the Discussion of History of Chemistry in February 2018 and the Oxford Seminar History of Alchemy and Chemistry in January 2018. Presenting this paper at PSA 2018 was enabled by grants from the Society of History of Alchemy and Chemistry and the Oskar Huttunen Foundation.