When Was the Periodic Table First Published?

Russian chemist Dmitri Mendeleev presented his periodic table to the Russian Chemical Society on March 6, 1869, organizing 63 known elements by atomic weight and chemical properties. His genius lay in leaving gaps for elements not yet discovered, predicting their properties with remarkable accuracy. When gallium was discovered in 1875 and germanium in 1886, matching his predictions almost exactly, the scientific world embraced his system. The modern table, organized by atomic number rather than weight, contains 118 confirmed elements as of 2024.