![Mendeleev and the periodic table](/content/images/size/w600/2024/03/Mendeleev.webp)
Mendeleev and the periodic table
At the turn of the nineteenth century, John Dalton proposed the atomic theory. He proposed each element comprises atoms of a single, unique type, and that these atoms could combine in fixed ratios to form compounds. Scientists raced to find more of these “pure” elements - hydrogen, oxygen, nitrogen, and