Kacey Gruber
Chem 2
10/6/14
J.J Thomson
Discovery of the Electron Joseph John Thomson also known as J.J Thomson was born December 18,
1856 in Cheetham, Manchester and died August 30, 1954. J.J. Thomson was the son of Emma Thomson and Joseph James Thomson , an antic bookseller and publisher. At age fourteen, Thomson attended Owen college where he studied engineering, mathematics, physics and chemistry. In 1876 he enrolled in Trinity college, in
Cambridge, receiving a scholarship for math. Finishing top of his class four years later.
Thomson continued his studies in physics and worked with Lord Rayleigh at Cavendish
Laboratory after becoming a fellow of Trinity College. After receiving his fellowship in
1881, he studied mathematics which also applied to many different branches of physicsThomson and Rose had two children, George Paget Thomson who also became physicist himself and Joan Paget Thomson who often joined her father in his work. J.J. Thomson was most commonly known for his discovery of the Electron, by conducting many different experiments in a high vacuum cathode ray tube, which was a tube that creates a visual presentation when an electron beam strikes a phosphorescent surface. Thomson began studying cathode rays in 1894. When he did his research he conducted that when rays pass through the vacuum, he could measure the angle at which they were deflected and calculate the ratio of the electrical charge to the mass of
the particles. He realized that the ratio was the same regardless of what type of gas was used, which then conclude that the particles that made up the gases were universal.
Though his experiments Thomson discovered that the strange particles he found had a negative charge. Which proved Dalton’s theory of an atom wrong, that the atom was filled with equal negative and positive charges. In 1906 ,being the first to use mass spectrometry, he started studying positive rays, which led him to discover that neon was composed of two different kinds of atoms.
Another theory J.J. Thomson proposed was the idea of the Plum Pudding model, (Chocolate chip model or the Blueberry muffin model.) This model was named the Plum Pudding model because both are very similar, the pudding itself is positively charged and the plum pieces are the negatively charged particles. Although today the accepted model today has a positively charged nucleus instead of the whole atom itself being positive, the plum pudding representation explains why atoms were neutral.
Thomson 's model lasted for five years until his student, Ernest Rutherford conducted an experiment to probe the atom. In Rutherford's experiment alpha particles coming from a radioactive source were directed to a gold foil. The foil was surrounded by a wall of zinc sulfide that showed tiny flashes
