Search results
Results From The WOW.Com Content Network
A schematic of the nucleus of an atom indicating β − radiation, the emission of a fast electron from the nucleus (the accompanying antineutrino is omitted). In the Rutherford model for the nucleus, a red sphere was a proton with positive charge, and a blue sphere was a proton tightly bound to an electron, with no net charge.
Sir James Chadwick (20 October 1891 – 24 July 1974) was an English physicist who received the Nobel Prize in Physics in 1935 for his discovery of the neutron. In 1941, he wrote the final draft of the MAUD Report , which inspired the U.S. government to begin serious atom bomb research efforts.
The prevailing model of atomic structure before Rutherford's experiments was devised by J. J. Thomson. [1]: 123 Thomson had discovered the electron through his work on cathode rays [2] and proposed that they existed within atoms, and an electric current is electrons hopping from one atom to an adjacent one in a series.
In 1932, Rutherford's theory of neutrons was proved by his associate James Chadwick, who recognised neutrons immediately when they were produced by other scientists and later himself, in bombarding beryllium with alpha particles. In 1935, Chadwick was awarded the Nobel Prize in Physics for this discovery.
The two types of beta decay are known as beta minus and beta plus.In beta minus (β −) decay, a neutron is converted to a proton, and the process creates an electron and an electron antineutrino; while in beta plus (β +) decay, a proton is converted to a neutron and the process creates a positron and an electron neutrino. β + decay is also known as positron emission.
JJ Thomson's model was the first of these models to be based on experimentally detected subatomic particles. In the same paper that Thomson announced his results on "corpuscle" nature of cathode rays , an event considered the discovery of the electron , he began speculating on atomic models composed of electrons.
Get AOL Mail for FREE! Manage your email like never before with travel, photo & document views. Personalize your inbox with themes & tabs. You've Got Mail!
1932 James Chadwick discovers the neutron; 1932 John Cockcroft and Ernest Walton split lithium and boron nuclei using proton bombardment; 1932 Werner Heisenberg presents the proton–neutron model of the nucleus and uses it to explain isotopes; 1933 Ernst Stueckelberg (1932), Lev Landau (1932), and Clarence Zener discover the Landau–Zener ...