Atomic Model (Part 3: The Thomson's Atomic Model)

After decades of Dalton put forward his theory of the call with the Doubled Multiple Law, the theory of the atom is growing by leaps and bounds. Since the discovery of electron as an elementary particle wich is negatively charged, the validity of Dalton's atomic theory began to be questionable. In 1899, a British phisicist, Sir Joseph Thomson, proposed an atomic model caled Raisin Plum Pudding Model. Thomson described atom as a positively charge sphere containing several negatively charged particle called electron. The electrons are scattered in the sphere like raisin in a plum pudding. 

In 1904 Thomson suggested a model of the atom as a sphere af positive matter in which electronare positioned by electrostatistic force. His efforts to estimate the number of electrons in a atom from measurement of the scattering of light, X, Beta, and gamma rays initiated the research trajectory along which his student Ernest Rutherford moved. Thomson's last important experimental program focused on determining the nature of positively charged particles. Here his techniques led to the development of the mass spectrogaph.

Next-Atomic Model (Part 4: The Rutherford's Atomic Model)