James Chadwick (1932)

Chadwick discovered the neutron in 1932 and proved Ernest Rutherford’s atomic theory to be correct. Chadwick exposed several substances and elements to radiation and then measured the recoil atom energy. After this experiment Chadwick concluded that there was a particle that was the same size as a proton with a neutral charge and thus proving the atomic theory that Rutherford and Bohr proposed to be correct. Chadwick also discovered the ability to split the nuclei and opened the door for the creation of the atomic bomb.