JJ+Thomson-1897

JJ Thomson was born on December 18, 1856 in Cheetham Hill, Manchester England. He lived to be 86 when he died on August 30, 1940. He is credited for the discovery of the electron and isotope, conduction of electricity in gases, as well as the invention of the mass spectrometer. In 1905, Thomson discovered the natural radioactivity of potassium. In 1906, Thomson demonstrated that hydrogen had only a single electron per atom which conflicted with previous beliefs. He was awarded the Nobel Prize in 1906 for physics. His son won the Nobel Prize in 1937 for proving the wavelike properties of electrons. Thomson also was a teacher of Ernest Rutherford at Trinity College, Cambridge.

Thomson conducted a series of experiements with cathode rays and cathode ray tubes that led him to discover electron and subatomic particles. He used the cathrode ray tube in three different experiments. These three experiments led him to these discoveries: 1. The negatively charged cathode was known to be the source of the cathode rays 2. The cathode rays were known to have the particle-like property of charge 3. Electrons were deflected by a magnetic field like a negativley charged particle 4. Electrons had the wave-like property of being able to penetrate thin, metal foils 5. Electrons had not yet been subject to deflection by an electric field While conducting an experiment with neon, Thomson noticed that two different patches of light came from the element. This led him to discover that neon is composed of atoms of two different atomic masses. This was the birth of the isotope.

A cathode ray tube