Search results
Results From The WOW.Com Content Network
Thomson made the discovery around the same time that Walter Kaufmann and Emil Wiechert discovered the correct mass to charge ratio of these cathode rays (electrons). [36] The name "electron" was adopted for these particles by the scientific community, mainly due to the advocation by George Francis FitzGerald, Joseph Larmor, and Hendrik Lorentz.
In 1927, George Paget Thomson and Alexander Reid discovered the interference effect was produced when a beam of electrons was passed through thin celluloid foils and later metal films, and by American physicists Clinton Davisson and Lester Germer by the reflection of electrons from a crystal of nickel. [62]
In 1891, he proposed the term "electron" to describe the fundamental unit of electrical charge, [7] and his contributions to research in this area laid the foundations for the eventual discovery of the particle by J. J. Thomson in 1897. His scientific work was carried out in his spare time. [8]
1932 Antielectron (or positron), the first antiparticle, discovered by Carl D. Anderson [13] (proposed by Paul Dirac in 1927 and by Ettore Majorana in 1928) : 1937 Muon (or mu lepton) discovered by Seth Neddermeyer, Carl D. Anderson, J.C. Street, and E.C. Stevenson, using cloud chamber measurements of cosmic rays [14] (it was mistaken for the pion until 1947 [15])
The electrons in these tubes moved in a slow diffusion process, never gaining much speed, so these tubes didn't produce cathode rays. Instead, they produced a colorful glow discharge (as in a modern neon light ), caused when the electrons struck gas atoms, exciting their orbital electrons to higher energy levels.
Helium, for instance, was thought to have four protons and two nuclear electrons in the nucleus, leaving two excess protons and a net nuclear charge of 2+. After the neutron was discovered, scientists realized the helium nucleus in fact contained two protons and two neutrons.
† Elements with 7p electrons have been discovered, but their electronic configurations are only predicted – save the exceptional Lr, which fills 7p 1 instead of 6d 1. ‡ For the elements whose highest occupied orbital is a 6d orbital, only some electronic configurations have been confirmed.
By modern convention, the charge carried by electrons is defined as negative, and that by protons is positive. [33] Before these particles were discovered, Benjamin Franklin had defined a positive charge as being the charge acquired by a glass rod when it is rubbed with a silk cloth. [34]