The periodic table
Russian chemist (1834-1907) who organized the elements into a predictive pattern.
He laid out the known elements by weight and properties — then boldly left gaps, predicting the existence and traits of elements not yet discovered. When gallium and germanium turned up exactly as forecast, the table became chemistry's master map.
Dmitri Mendeleev is one of the historical characters you can play as in Rubicon, a trivia game where you answer in your own words and an AI judge reads what you meant. Dmitri Mendeleev is filed under Natural Sciences, and is strongest at Natural Sciences.