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English J. J. Thomson (1856-1940)
- Discovered electron (negatively charged particle
- Charge to mass ratio of e- is constant, this means only one type of electron
- From results of his experiment, Plum pudding Model of Atom
American Robert Millikan (1868-1953)
- Determined actual charge and mass of e-, mass of electron = 9.11E-28 g
- Used a sensitive oil dropping equipment
- Discovery made in 1909
German Eugene Goldstein (1850-1930)
- Discovery of proton (some people dispute this)
- When, about same time as electron, also disputed
English James Chadwick (1891 – 1974)
- Discovery of neutron, 1932
Subatomic Particle Data
- Proton (p+), positively charged, mass = 1.67E-24 g, located in nucleus
- Neutron (n0), neutral charge, mass = 1.67E-24 g, located in nucleus
- Electron (e-), negatively charged, mass = 9.11E-28 g, located outside nucleus
- electron mass is approximately 1/2000 mass of proton or neutron (actually is 1/1840)
- Note: Yes, these subatomic particles are made up of even smaller particle, but that is for physic to explain NOT chemistry.