Dmitry Mendeleyev

(1860s – 1870s) Realized that if all of the 63 known elements are arranged in order of increasing atomic weight, their properties are repeated according to certain periodic cycles. He formulated the periodic table of the elements and predicted the existence of elements that have not yet been discovered. Three of those elements were found during his lifetime: gallium, scandium and germanium.

History & Mythology >Discoveries