His theory was that atoms where solid spheres. The different spheres represented the different elements.
J.J. Thompson developed Dalton's theory using the Plum Pudding Model. This model was the idea of a positively charged sphere with fixed negatively charged electrons as he concluded that there was smaller negatively charged particles from his measurements of mass and charge.
He tested this theory with the Gold Foil Shattering Experement. Rutherford shot positive alpha particles at thin gold foil expecting that the particles would reflect slightly and most go directly through the foil. However, this wasn't…