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An atom with seven electrons arranged in a pentagonal dipyramid, as imagined by Thomson in 1905. The plum pudding model is an obsolete scientific model of the atom.It was first proposed by J. J. Thomson in 1904 following his discovery of the electron in 1897, and was rendered obsolete by Ernest Rutherford's discovery of the atomic nucleus in 1911.
In 1904, Thomson suggested a model of the atom, hypothesizing that it was a sphere of positive matter within which electrostatic forces determined the positioning of the corpuscles. [2] To explain the overall neutral charge of the atom, he proposed that the corpuscles were distributed in a uniform sea of positive charge.
Almost a century later, Joseph John Thomson, a fellow Mancunian working the University of Cambridge in 1897, discovered the electron, proving that the atom had smaller constituent parts.
According to Thomson's model, all of the alpha particles should have passed through with negligible deflection. Rutherford deduced that the positive charge of the atom is not distributed throughout the atom's volume as Thomson believed, but is concentrated in a tiny nucleus at the center. This nucleus also carries most of the atom's mass.
Between 1870 and 1890 the vortex atom theory, which hypothesised that an atom was a vortex in the aether, was popular among British physicists and mathematicians. William Thomson, who became better known as Lord Kelvin, first conjectured that atoms might be vortices in the aether that pervades space. About 60 scientific papers were subsequently ...
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 ...
In 1898, J. J. Thomson found that the positive charge of a hydrogen ion is equal to the negative charge of an electron, and these were then the smallest known charged particles. [22] Thomson later found that the positive charge in an atom is a positive multiple of an electron's negative charge. [23]
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. In 1904, Nagaoka proposed an alternative planetary model of ...