Today in History—March 6: The Introduction of the Periodic Table

On this day in 1869, Russian chemist Dmitri Mendeleev took a break from improving cheese-making techniques to show the world how he’d rearranged the known universe.

His paper, “The Dependence Between the Properties of the Atomic Weights of the Elements”—the first periodic table arranged horizontally and vertically by property—was presented at a meeting of the Russian Chemical Society.

Once he got into college (it was a rocky road), he took to science. His dissertation was published in a mining journal. His master’s thesis explored relationships between volumes of substances and their chemical properties—a sign he was already looking for patterns. He became a chemistry tutor at the University of St. Petersburg and, in 1859, secured study abroad.

And that’s how he ended up at a German conference where an Italian chemist presented groundbreaking work on atomic weight. That was the missing piece in the periodic puzzle: introducing a standard (oxygen = 16) by which to measure atomic weights of elements. (Other, less helpful options included ignoring the weights or pretending atoms didn’t exist.)

Back in Russia, Mendeleev earned his doctorate and became a chemistry professor. He was assigned to teach inorganic chemistry, so he began writing a textbook. In the process, he started arranging elements.

Volume one came together quickly. Then he got distracted. Mendeleev was always using his skills in practical ways to improve Russian industries: Cheese-making was one interest; petroleum refining, luggage crafting, and shipbuilding were others.

But he soon returned to volume two.

At the time, about 60 elements were known. No one had ever successfully organized them. Mendeleev noticed that when he made a grid—like the solitaire games he liked—patterns in properties repeated periodically. He trusted this pattern enough to leave gaps for elements that hadn’t even been discovered yet.

A longer version of his work was published later that year and translated into German, slowly spreading his ideas. Time helped too: The discovery of gallium, scandium, and germanium a few years later—with properties Mendeleev had predicted—forced chemists to take notice.

His table wasn’t perfect. He couldn’t have known that atomic number, not mass, was the key. But he saw something no one else had.

Scientists named element 101, mendelevium, after him. Mendeleev had literally become part of his masterpiece.