1904, Thomson's Plum Pudding

Year: 1904
Chemist: Joseph John Thomson
Contribution: Thomson's Plum Pudding Model

Photo Credit: dflit.wikispaces.com
Seven years after his discovery of electrons, J.J. Thomson developed a new atomic model, called, "Thomson's Plum Pudding." It was Thomson's belief that atoms are positively charged, identical spheres. The electrons in this model were "baked" into the center of the atom, much like fruit cake or plum pudding.

It was replaced in 1911 for Ernest Rutherford's model.

Information Credit: Encyclopedia Britannica