PROTON: Positive (+) charge. Relative mass of 1. Found in the nucleus.
NEUTRON: Neutral charge. Relative mass of 1. Found in the nucleus.
ELECTRON: Negative (-) charge. Relative mass of .0005. Found on the outside of the nucleus.
Chadwick proved the existence of neutrons - elementary particles devoid of any electrical charge.
Rutherford discovered alpha and beta rays and proposed the mass of radioactive decay. Postulated the nuclear structure of the atom.
J.J Thompson proposed the plum pudding model of the atom. Showed that all atoms contain tiny negatively charged subatomic particles or electrons.