Chemistry

Democritus
4BC, discovered that the smallest part of any given object is an atom
Dalton
1810, said that the atom was the smallest INDIVISIBLE particle (false)
JJ Thompson
1897, found electrons and protons (Plum Pudding model)
Rutherford
1911, said that protons are in the middle and that electrons revolve around them (focused alpha particles)
Chadwick
1932, discovered the neutron