The Periodic Table – A Common Language for Science
In 1869, Dmitri Mendeleev presented his version of the periodic table of the elements, and this event fundamentally changed the course, not only of chemistry, but of all the natural sciences. To honour the 150th anniversary of this ground-breaking innovation, the United Nations General Assembly and UNESCO declared 2019 to be the International Year of the Periodic Table of Chemical Elements.
While the history of the periodic table – like so many things in our culture – harks back to antiquity, the great boom in the discovery of the elements – and, at the same time, the definition of the notion ‘element’ – came in the second half of the 18th century. The first complete list of the elements known in the era was written in 1789 by Antoine-Laurent de Lavoisier, who first introduced the distinction between metals and non-metals. At the beginning of the 19th century, the scope of discoveries widened and there was a need for an organised overview of the discovered elements. The keyword was periodicity, all the proposed systems tried to find some similarities by which the elements could be catalogued. It was Mendeleev’s system, however, that not only managed to highlight the periodically repeating nature of elements arranged according to their atomic mass, but also succeeded in predicting with great accuracy the position and the attributes of some missing elements that were discovered later (e.g., gallium, germanium).
Nevertheless, the periodic table is not a static idea, as scientists are still working on discovering further elements while predicting new ones based on the regularities of the periodic table. Most of these new elements (like the most recent one, tennessine) are discovered in laboratory conditions and cannot possibly be found in nature. While, at the moment, the element with the largest atomic number is oganesson (118), scientists are looking for new methods (including quantum mechanics) to further expand the table.
The nomenclature of the elements is another interesting aspect of the periodic table. Many names are of Latin and Greek origin (e.g. helium, neon), but surprisingly we can find names with either Arabic (boron), Egyptian (natrium, i.e. sodium), or Anglo-Saxon (lead) roots. Many recently discovered elements are either provided with geographical names (berkelium after Berkeley, California) or names honouring scientists (curium). In the case of new and undiscovered elements, temporary names are regulated by the International Union of Pure and Applied Chemistry (IUPAC), which are derived from their atomic number. For example, element 118, oganesson, was once called ununoctium. Nevertheless, all the discovered elements have now received their permanent names and symbols, thus this systematic nomenclature is only relevant for undiscovered elements beyond oganesson.
There are so many exciting aspects of the periodic table that cannot be explored within the framework of a blog entry. The year-long celebration of the 150th anniversary of the periodic table, however, provides many different viewpoints in order to discover the long-lasting effect of Mendeleev’s innovation, from scientific conferences to online quizzes and art projects.
Written by Zsolt Beke