1938 Otto Hahn & Lise Meitner
While working in a lab, Otto Hahn discovered radiothorium, and then later discovered 5 more elements. He also discovered radioactive recoil. Lise Meitner was he partner when they discovered the isotope of protactinium. His biggest discovery was barium as a fission element. He combined results with Otto Frisch and they came up with nuclear fission. He was testing uranium and how it busted into lighter elements. Lise always studied radioactivity. She, herself, discovered the auger effect.