1 jan 1911 ano - Ernest Rutherford

Descrição:

Ernest Rutherford was born to British parents in 1871 in New Zealand (Badash, 2020). His contribution to the atomic model was one of the most important steps towards the current model.

In 1909, Rutherford conducted the famous gold foil experiment, in which he fired positively charged alpha particles, which are helium nuclei, at a thin gold foil (Badash, L, 2020). He measured the angles at which these alpha particles were deflected by surrounding the foil with fluorescent screens and observing the scintillations (Badash, 2020).

He was surprised to find that some alpha particles had been deflected at large angles, greater than 90 degrees, while others passed through the foil and deflected at lesser angles- the results did not agree with Thomson's plum pudding model (Badash, 2020).

In 1911, he concluded that such a heavy charged particle as an alpha particle could only be deflected as observed by electrostatic forces if the atom was not a uniform solid like Thomson had proposed (Badash, 2020). Instead, the atom would require a relatively heavy and small positively charged centre, or nucleus, with negatively charged electrons orbiting around it at a considerable distance (Badash, 2020). The mass of the atom was concentrated in the nucleus, which was made of protons, and the atom was composed of mostly empty space (Badash, 2020).

Rutherford had discovered the nucleus of the atom, which would later be found to include neutrons, and took an instrumental step towards arriving at the current atomic model.

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