Period+4+Thomson


 * // media type="custom" key="2365281"[|J.J. Thomson] was born in Cheetham Hill on December 18, 1856. He attended Owens College in Manchester in 1870. In 1876, he entered Trinity College in Cambridge as a minor scholar. He remained a member of the College for the rest of his life becoming Lecturer in 1883 and Master in 1918. His [|Treatise on the Motion of Vortex Rings] was a reflection of his interest about atomic structure, which won him the Adam Prize in 1884. Thomson worked with cathode rays and believed them to be particles mainly because they were deflected in magnetic fields. He started to explore X rays and demonstrated their power to make a gas electrically conductive. After this he returned to his research on [|cathode rays] . He decided that cathode rays were negatively charged because of the way they were deflected in one of his experiments and because the charge to mass ratio was always the same. He suggested that the arrangement and number of these cathode rays, later named electrons, would determine the chemical properties of an element. He discovered the electron using a cathrode ray tube in 1897. Thomson calculated its mass to charge ratio and proposed the plum pudding model of the atom. He produced a theory of how matter was made up called the "Plum Pudding Model". In the Plum Pudding Model, each atom was a sphere filled with a positively charged fluid, which they called the "pudding". Throughout this fluid were electrons known as "plums". Thomson had suggested that the positive fluid held negative charges, which were the electrons, in the atom because of electrical forces. This however failed to provide any definite answers. However, this was later proved inaccurate. Thomson became the first person to separate isotopes of the chemical element and in 1913 he found that neon had two forms (isotopes) differing only in weight. He discovered the electron, isotopes, and the mass spectrometer. He discovered a method for separating different kinds of atoms and molecules by the use of positive rays, an idea developed by Aston, Dempster and others towards the discovery of many isotopes. Thomson proposed an aromic model theory in 1904 in response to the curiousities of some scientists. They thought that positive particles might exist to balance the negative particle, and were curious about how many charged particles were in the atom. Thomson wrote a book called, //Conduction of Electricity through Gases//, published in 1903. Other books he published include// The Structure of Light//,// The Corpuscular Theory of Matter//,// Rays of Positive Electricity//,//The Electron in Chemistry //and his autobiography,// Recollections and Reflections//. He was elected Fellow of the Royal Society in 1884 and was President during 1916-1920. Thompson was also awarded the Hodgkins Medal in 1902; the Franklin Medal and Scott Medal (Philadelphia) in 1923; the Mascart Medal in1927; the Dalton Medal (Manchester) in1931; and the Faraday Medal (Institute of Civil Engineers) in 1938. He also won the Royal Medal, the Hughes Medal, and the Nobel Prize for Physics, and the Copley Medal. Throughout his life he obtained many honorary doctorate degrees from many universities such as Oxford, Dublin, Cambridge, Princeton, John Hopkins, ect.//**

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