Rutherford in his alpha scattering experiment bombarded a thin gold foil with alpha particles. He found that most of the alpha particles passed through the coil undeflected while a few of them were deflected back. To explain this, he suggested an atomic model (the nuclear model) in which an atom has a small positively charged centre (nucleus) where all the mass is concentrated, and a large space surrounding the nucleus where the electrons are found.
J. J. Thompson is credited with the discovery of the electrons (cathode rays) and their charge to mass ratio, Millikan's oil - drop experiment was used to determine the charge on an electron \(\left(1.60 \times 10^{-19} C \right)\) while Dalton proposed the so-called Dalton's atomic theory