Think the current Periodic Table of chemical elements are neat and elegant? When it first debuted in the mid-nineteenth century, it looked nothing like what it is now: it only has 60 elements and multiple placeholders for yet-to-be-discovered elements.
Although other pioneering scientists such as British chemist John Newlands, French geologist Alexandre Béguyer de Chancourtois and German chemist Julius Lothar Meyer all made undeniably significant contributions to the Periodic Table, Dmitri Mendeleev was credited as the main originator.
What's so special about Mendeleev's version? Compared to the others, he did a more accurate calculation of the relative mass of different atoms, so all elements were placed in their correct places on the table.
Also, he left empty spaces for elements that were not yet discovered, and he predicted properties of five of these elements. Within the 15 years after the release of his Periodic Table, three of these missing elements were discovered by others.
Source: ACSReactions via Youtube