In 1908, Ernest Rutherford, with the help of Hans Geiger and Ernest Marsden, conducted a series of experiment with the purpose of refining the structure of the atom and resolving some problems that the previous model presented. The excepted atomic structure at the time was the Thompson model which envisioned the atom as a positively charged atomic field with negatively charged electrons scattered within. This theory was known as the “Plum Pudding” model because the electrons resembled raisins scattered about a positively charged “pudding”. While important in the development of the atomic structure, the Thomson model presented some problems that contradicted established laws of physics. For instance this model failed to explain the neutrality of the atom as well as contradicted the calculated mass of the atom.

The experiment conducted by Rutherford served to redefine our interpretation of the atom and resolve the problems present in the Thomson model. The tests conducted consisted of a thin sheet of gold foil surrounded by a particle-detecting ring. Positively charged alpha particles were fired into the gold sheet and the deflected particles were then detected by the ring. Rutherford observed that while most of the particles traveled straight through the gold sheet, which would have been expected given the Thomson model, some of the particles were defected at odd angles with some even being reflected right back into the emitter. This contradicted Thomson’s theory of the atom having a positively charged field making up most of its space because, applying Coulomb’s law, Rutherford knew that the field could not defect the positively charged alpha particles at such intense angles as was observed. Rutherford concluded that the atom was mostly empty space with negative electrons orbiting a