Atom is not a plum pudding
J. J. Thomson suggested in
that the atom is composed of electrons surrounded by a soup of positive charge to balance the electrons' negative charges, like negatively charged "raisins" surrounded by positively charged "pudding". The
Thomson model was disproved by the
gold foil experiment of Hans Geiger and Ernest Marsden, and this was interpreted by Ernest Rutherford in
The above right top is the expected result: alpha particles passing through the plum pudding model of the atom undisturbed. The above right bottom is the observed result: a small portion of the particles were deflected. Which of the following statements best explains the observed result?
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Alfa particles are positively charged. As gold is least reactive, the only reason behind repulsion of alfa particles could be presence of positive charge in the nucleus of the atom. As most of the alfa particles went through undisturbed, nucleus is present in very small concentration.