| Under the prevailing plum pudding model, the alpha particles should all have been deflected by, at most, a few degrees; measuring the pattern of scattered particles was expected to provide information about the distribution of within the atom | It was then that I had the idea of an atom with a minute massive center, carrying a charge |
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| Although many of the alpha particles did pass through as expected, many others were deflected at small angles while others were reflected back to the alpha source |
It was almost as incredible as if you fired a 15-inch shell at a piece of tissue paper and it came back and hit you.
21| On consideration, I realized that this scattering backward must be the result of a single collision, and when I made calculations I saw that it was impossible to get anything of that order of magnitude unless you took a system in which the greater part of the mass of the atom was concentrated in a minute nucleus | They observed that a very small percentage of particles were deflected through angles much larger than 90 degrees |
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| Note that the image is not to scale; in reality the nucleus is vastly smaller than the electron shell | series of experiments 1908-1913 by Hans Geiger and Ernest Marsden, directed by Ernest Rutherfofrd, at the University of Manchester, proving the existence fo the atomic nucleus through alpha particle scattering on gold foil |
However, the actual results surprised Rutherford.
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