1. Dmitri Mendeleev, Periodic Table
Dmitri Mendeleev (1834–1907) wanted to organize the 65 known elements somehow. He knew there was a pattern to be discerned, and it had something to do with atomic weight, but the pattern remained elusive. Then, Mendeleev later reported, “In a dream I saw a table where all the elements fell into place as required. Awakening, I immediately wrote it down on a piece of paper.” Mendeleev’s words were quoted in “On the Question of Scientific Creativity,” by Russian chemist B.M. Kedrov.
A painting of Dmitri Mendeleev, 1878, by Ivan Nikolaevich Kramskoi. Public domain
