Mendeleev's Periodic Table

March 1, 1869

In St. Petersburg, a shaggy chemist named Dmitri Mendeleev arranged the sixty-three known elements into a grid by atomic weight and found, miraculously, that their properties repeated. Where the grid had gaps, he predicted new elements with specific properties. They kept being found. Chemistry had its fundamental map. Gallium, scandium, and germanium all appeared within fifteen years, exactly as Mendeleev had predicted, vindicating his audacious grid.