J.J. Thomson – Discovery of the Electron

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CHE003 Chemistry
Individual Assignment
J.J. Thomson – Discovery of the electron

Table of Contents


Biographical information3

Background information4

Experimental information5



J.J. Thomson – Discovery of the electron


The discovery of the electron is affirmative and justly credited to the English physicist Sir Joseph John Thomson (Weinberg, 2003). He had found and identified the electron in Cavendish Laboratory, Cambridge in 1897. From many experiments, Thomson had certified that cathode rays carry negative charge and identified the cathode rays inside vacuum tubes as being electric currents composed of these tiny electrons (Hamblin, 2005). It was the crucial first step in the development of the twentieth-century concept of the atom (Simmons, 1996). In the following paragraphs, I will introduce the Thomson’s life and his important achievements.

Biographical information

J.J. Thomson was born at Cheetham Hill, a suburb of Manchester, England on December 18, 1856. His father Joseph Thomson was a publisher and book dealer; his mother was Emma Swindles, a housewife. The family’s environment was not good for learned, but he was excellent in study and had an exceptional memory. When Thomson was fourteen in 1870, he enrolled in Owens College and had been taught by the physics professor, Balfour Stewart. Then he entered Trinity College in 1876, as a minor scholar. In 1880, Thomson became a Fellow of Trinity College, when he was Second Wrangler and Second Smith's Prizeman; he remained at Cambridge for the rest of his life, and becoming lecturer in 1883. In 1884, Thomson was named Cavendish Professor of Experimental Physics at an exceptionally young age (Simmons, 1996). On April 30, 1897, was his first time announced preliminary discovery of electron during lecture in Royal Institute, England. In 1903, Thomson published a summary of his work; Conduction of electricity through gases, and he created the “plum-pudding” model, which is the first model of atom. Thomson won the Nobel Prize for Physics in 1906, a knighthood in 1908, and the Presidency of the Royal Society in 1915. He was also a member of the Board of Investigation and Research, which served Britain in World War One (Weinberg, 2003). After that, he resigned from the Cavendish Laboratory in 1919 to become Master of Trinity College, until died on August 30, 1940 (Hamblin, 2005).

In addition, he married with Rose Elisabeth in 1980, they had one son; George Paget Thomson; also won the Nobel Prize for Physics in 1937, and one daughter.

Background information

In the end of nineteenth century and the beginning of the twentieth century were exciting and revolutionary time for physics (Franklin, 2004). They began to investigate the behavior of electricity in evacuated tubs. The conduction of electricity through a near vacuum appeared to produce a kind of “ray”, lighting up the inside of the tube. The cathode rays appeared to be like light, and thus some physicists concluded that they were wave but other evidence proofed that the rays were in fact material in nature. During 1894 to 1897, Thomson was investigated the phenomenon of cathode ray, which had been discovered in 1858 (Ne’eman& Kirsh, 1997). In 1897, he made a significant discovery that the “rays” were indeed built up of particles and that they were the constituents of all atom. Thomson believed that his experimental evidence, by electromagnetic deflection and measuring the kinetic energy of the ray, had proven it. In the first, he did not initially call it electron, but chose the word “corpuscle” to emphasize the material nature of the particle. Thomson had found the new particle was very much matter, and he believed that it was the fundamental form of matter in atoms (Hamblin, 2005). Moreover, Albert Einstein introduced his special theory of relativity, which fundamentally changed our concepts of space and time in 1905. Follow by...
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