CHEM 130 Chapter Notes - Chapter 1.6-1.7: Charge Radius, Ernest Rutherford, Plum Pudding Model

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13 Oct 2016
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1. 6 - early experiments to characterize the atom. J j thomson - when high voltage was applied to cathode-ray tubes, a. Cathode ray (emanates from negative electrode - aka cathode) was produced the ray was a stream of electrons. Charge to mass ratio: (e/m) = -1. 76*10^8 (c/g) Concluded that all atoms must contain electrons. Plum pudding model - negative electrons are dispersed randomly in positive cloud. Robert millikan - tried to determine magnitude of electron charge. Henri becquerel - piece of mineral w/ uranium could produce its image on a photographic plate in the absence of light. Said this was due to uranium"s radioactivity. +2 charge - a charge twice that of electron and w/ the opposite sign. Mass = 7300 times that of electron. Ernest rutherford - large deflection of alpha particles center of concentration of + charge that contains most of the atom"s mass. Deflected alpha particles = closer to center. Reflected alpha particles = hit the center.