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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 features of a relatively high central charge concentrated into a very small ...
The prevailing model of atomic structure before Rutherford's experiments was devised by J. J. Thomson. [1]: 123 Thomson had discovered the electron through his work on cathode rays [2] and proposed that they existed within atoms, and an electric current is electrons hopping from one atom to an adjacent one in a series.
Ernest Rutherford, 1st Baron Rutherford of Nelson, (30 August 1871 – 19 October 1937), was a New Zealand physicist who was a pioneering researcher in both atomic and nuclear physics. He has been described as "the father of nuclear physics", [ 7 ] and "the greatest experimentalist since Michael Faraday ". [ 8 ]
The current theoretical model of the atom involves a dense nucleus surrounded by a probabilistic "cloud" of electrons. Atomic theory is the scientific theory that matter is composed of particles called atoms. The definition of the word "atom" has changed over the years in response to scientific discoveries.
A schematic of the nucleus of an atom indicating β − radiation, the emission of a fast electron from the nucleus (the accompanying antineutrino is omitted). In the Rutherford model for the nucleus, a red sphere was a proton with positive charge, and a blue sphere was a proton tightly bound to an electron, with no net charge.
Thomson's model marks the moment when the development of atomic theory passed from chemists to physicists. While atomic theory was widely accepted by chemists by the end of the 19th century, physicists remained skeptical because the atomic model lacked any properties which concerned their field, such as electric charge, magnetic moment, volume, or absolute mass.
1909 Ernest Rutherford and Thomas Royds demonstrate that alpha particles are doubly ionized helium atoms; 1909 Hans Geiger and Ernest Marsden discover large angle deflections of alpha particles by thin metal foils; 1911 Ernest Rutherford explains the Geiger–Marsden experiment by invoking a nuclear atom model and derives the Rutherford cross ...
Secondly, he found the charge-to-mass ratio of alpha particles to be half that of the hydrogen ion. Rutherford proposed three explanations: 1) an alpha particle is a hydrogen molecule (H 2) with a charge of 1 e; 2) an alpha particle is an atom of helium with a charge of 2 e; 3) an alpha particle is half a helium atom with a charge of 1 e.