A little leeway – that’s what Dmitri Mendeleev showed in 1869 when he invented the periodic table of the elements. When he arranged the chemical elements known at the time into a logical order, he came to the conclusion that there must be other, as yet unknown elements. He left some space in his periodic table for them. A few years later, Mendeleev’s assumption turned out to be correct, and newly discovered substances fit into the gaps.
In St. Petersburg, you can visit the place where Dmitri Mendeleev worked on this and other inventions. From 1866 to 1890, he lived in an apartment belonging to the State University of St. Petersburg. On display in the furnished apartment are, among other things, manuscripts, diaries, laboratory equipment, furniture and portraits of Dmitri Mendeleev, as well as the original draft of his periodic table.
Museum website: https://english.spbu.ru/about/st-petersburg-university-exhibitions-and-museum-collections/dmitri-mendeleev-museum-and
Photo: Periodic table of elements on a laboratory table. Credits: Unsplash/Vedrana Filipović.