Search results
Results from the WOW.Com Content Network
The plum pudding model was the first scientific model of the atom with internal structure. It was first proposed by J. J. Thomson in 1904 following his discovery of the electron in 1897, but it was subsequently rendered obsolete by Ernest Rutherford 's discovery of the atomic nucleus in 1911. The model tried to account for two properties of ...
The Rutherford model was devised by Ernest Rutherford to describe an atom. Rutherford directed the Geiger–Marsden experiment in 1909, which suggested, upon Rutherford's 1911 analysis, that J. J. Thomson 's plum pudding model of the atom was incorrect. Rutherford's new model [1] for the atom, based on the experimental results, contained new ...
While in Thomson's plum pudding model it is mathematically possible that an alpha particle could be deflected by more than 90° after 10,000 collisions, the probability of such an event is so low as to be undetectable. This extremely small number shows that Thomson's model cannot explain the results of the Geiger-Mardsen experiment of 1909.
To explain the overall neutral charge of the atom, he proposed that the corpuscles were distributed in a uniform sea of positive charge. In this "plum pudding model", the electrons were seen as embedded in the positive charge like raisins in a plum pudding (although in Thomson's model they were not stationary, but orbiting rapidly). [32] [33]
In 1904, Thomson suggested that the atom was a sphere of uniform positive electrification, with electrons scattered through it like plums in a pudding, giving rise to the term plum pudding model. Nagaoka rejected Thomson's model on the grounds that opposite charges are impenetrable.
Top: Expected results: alpha particles passing through the plum pudding model of the atom undisturbed. Bottom: Observed results: a small portion of the particles were deflected, indicating a small, concentrated charge. Diagram is not to scale; in reality the nucleus is vastly smaller than the electron shell.
Thomson's model is popularly known as the plum pudding model, based on the idea that the electrons are distributed throughout the sphere of positive charge with the same density as raisins in a plum pudding. Neither Thomson nor his colleagues ever used this analogy. It seems to have been a conceit of popular science writers.
The Thomson problem is a natural consequence of J. J. Thomson's plum pudding model in the absence of its uniform positive background charge. [ 12 ] "No fact discovered about the atom can be trivial, nor fail to accelerate the progress of physical science, for the greater part of natural philosophy is the outcome of the structure and mechanism ...