The Periodic System of the Chemical Elements

2019 has been designated by the United Nations and UNESCO as the International Year of the Periodic Table (IYPT2019), so on the evening of 7 November the section was delighted to welcome Prof Brigitte van Tiggelen from the Science History Institute (Philadelphia, USA and Paris) and le Centre de Recherche en Histoire des Sciences (UCLouvain, Belgium) to the British School of Brussels to talk to us about the origins of the Periodic System of the Chemical Elements.

The International Year of the Periodic Table (IYPT2019) coincides with the celebration of the anniversary of the first publication of the Periodic System by the Russian chemist Dmitry Ivanovich Mendeleev. However, Mendeleev was not the only one to propose a classification of all the elements then known, and he shared with Lothar Meyer the idea of making it a periodic system.

Brigitte's talk was entitled 'A work in progress: the Genesis and Development of the Periodic System' and covered the genesis of the periodic system including the significant contributions of scholars other than Mendeleev, such as Lothar Meyer; the question of the true significance of the predictions made by Mendeleev in the acceptance of the system by contemporaries, and the gradual but relatively slow dissemination of this tool within chemistry education. 

She also focused on the unique feature of Mendeleev's approach in his desire to produce a law of nature, the Periodic Law, that could be used to make predictions about the existence and sometimes even the properties of elements still to be discovered.

Brigitte described the development of the ideas behind the periodic system and the multiplicity of different periodic tables that have been generated over the century and half of its existence. In particular how it has adapted to successive new discoveries relating to the constitution of matter and its interpretation in terms of quantum mechanics. Not only could Mendeleev not have foreseen these developments, but he had a very hard time accepting the discovery of radioactivity and unstable elements, not to mention the isotopes of the elements, or the disruption of the atom and the atomic nucleus. 

Today, it is not possible to imagine the teaching or publication of a chemistry textbook that did not include a Periodic Table. But research conducted by historians of science show that the table did not enter the educational syllabus until quite late, demonstrating that what we now consider to be the indispensable and universal tool was absent from chemical training for many generations.

We hope to invite Prof Van Tiggelen back in 2020 to talk on the subject of 'Women in Science'. She has recently been the joint editor of an important book on the contribution of women to shaping the chemical sciences - 'Women in their Element' - that provides ample evidence of the female contributions to the iconic table of chemistry. The book shows how women contributed to the building and understanding of the periodic system and to the discovery of  many elements.