Abby Kane's List: Atom History Glog

• eph John Thomson was born in  Cheetham Hill, a suburb of Manchester on December 18, 1856.
• He was Cavendish Professor of Experimental  Physics at Cambridge, where he succeeded Lord Rayleigh, from 1884 to 1918 and  Honorary Professor of Physics, Cambridge and Royal Institution,  London.
• Thomson's early interest in atomic structure was reflected in his  Treatise on the Motion of Vortex Rings which won him the  Adams Prize in 1884. His Application of Dynamics to Physics  and Chemistry appeared in 1886, and in 1892 he had his  Notes on Recent Researches in Electricity and Magnetism  published. This latter work covered results obtained subsequent  to the appearance of James Clerk Maxwell's famous "Treatise" and  it is often referred to as "the third volume of Maxwell". Thomson  co-operated with Professor J. H. Poynting in a four-volume  textbook of physics, Properties of Matter and in 1895 he  produced Elements of the Mathematical Theory of Electricity  and Magnetism, the 5th edition of which appeared in  1921.
• an original  study of cathode rays culminating in the discovery of the  electron,
• important  suggestions as to the structure of the atom. He discovered a  method for separating different kinds of atoms and molecules by  the use of positive rays

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• In 1897 the British physicist Joseph John (J. J.) Thomson (1856–1940) discovered the electron in a series of experiments designed to study the
• nature of electric discharge in a high-vacuum cathode-ray tube
• Thomson interpreted the deflection of the rays by electrically charged plates and magnets as evidence of &quotbodies much smaller than atoms&quot that he calculated as having a very large value for the charge-to-mass ratio
• In 1904 Thomson suggested a model of the atom as a sphere of positive matter in which electrons are positioned by electrostatic forces
• determining the nature of positively charged particles
• able to discover isotopes
• nonmathematical atomic theory
• could also be used to account for chemical bonding and molecular structure

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• December 18, 1856
• discovery of the electron in 189
• and his subsequent investigations of these rays led him  to the idea that they consisted of bodies smaller than atoms.  Thomson's main contribution to science was the clear identification  of the electron and its characterization as an elementary, subatomic  particle in 1897. He showed that cathode rays were deflected by both  magnetic and electric fields, and he was able to measure a cathode  ray's charge/mass (    e/m    ) ratio
• cathode rays
•  

    Figure 1. Basic features of Thomson's apparatus.  
• plum pudding model of the ato
• negative plums embedded in a positively charged  pudding
• combination of electric and  magnetic fields to separate different charged atoms of elements on the  basis of their charge/mass ratios
• positive rays, which consist of ionized atoms

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