On February 8, 1834, in the freezing Siberian town of Tobolsk, Russia, a baby named Dmitri Ivanovich Mendeleev was born into a family with at least 13 brothers and sisters. His father went blind when Dmitri was little, and his mother ran a glass factory to keep everyone fed. When the factory burned down, she packed up young Dmitri and rode thousands of miles across Russia by sleigh to get him into a good university. She believed her brilliant youngest son was going to do something amazing.
She was right. Dmitri became a chemistry professor in St. Petersburg, but he was frustrated that nobody had a clean way to organize all the known chemical elements. He scribbled the names of every element he knew, with their weights, onto cards and shuffled them around like a giant deck of solitaire. The story goes that the perfect arrangement came to him in a dream in 1869. He woke up and sketched out a chart where elements lined up in neat rows and columns, with patterns repeating beautifully across the table.
Mendeleev's table even had empty spots, and he boldly predicted that new elements would be found to fill them, guessing their weights and properties. Within a few years, scientists found gallium, scandium, and germanium, exactly where he said they'd be. Today every chemistry classroom in the world has a colorful poster of his periodic table on the wall, and there's even an element named after him, mendelevium, number 101. Not bad for the youngest of 13.
