Rutherford's Experiment

Ernest Rutherford performed an experiment called 'Gold Foil Experiment' or 'a- ray scattering experiment' to test the structure of an atom as proposed by Thomson. In this experiment a beam of fast moving alpha particles ( positively charged helium ions ) was passed through a very thin foil of gold. He expected that the alpha particles would just pass straight through the gold foil and could be detected by a photographic plate. But, the actual results of the experiment were quite surprising. It was observed that most of the -particles did pass straight through the foil but a number of particles were deflected from their path. Some of these deflected slightly while a few deflected through large angles and about 1 in 10,000 'a- particles suffered a rebound.
These results led Rutherford to conclude that:
* the atom contained some dense and positively charged region located at the center of the atom that he called as nucleus.
* all the positive charge of the atom and most of its mass was contained in the nucleus.
* the rest of the atom must be empty space which contains the much smaller and negatively charged electrons.
The model proposed by Rutherford explained the observation in the -ray scattering experiments as shown below