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Period: to
Atomic Model
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John Dalton
formed the atomic theory, which states that all matter is composed of tiny, indestructible particles called atoms that are all alike and have the same atomic weight. Dalton developed an atomic theory to explain the ratios in which elements combine to form compounds. It was the cornerstone for modern atomic theory. -
Crookes
created the Crookes’ tube and demonstrated that cathode rays travel in straight lines and produce phosphorescence and heat when they strike certain materials. -
Becquerel
discovered radioactivity when he investigated uranium and other radioactive substances. -
The Curies
discovered radium and polonium when they started to investigate radioactive substances -
J.J Thomson
discovered the electron and developed the plum-pudding model of the atom. -
Max Planck
originated the quantum theory -
Albert Einstein
postulated that light was made up of different particles that, in addition to wavelike behavior, demonstrate certain properties unique to particles. He also brought forth the theory of relativity. -
Robert Millikan
found out the electric charge of the electron -
Ernest Rutherford
used the results of his gold-foil experiment to state that all the mass of an atom were in a small positively-charged ball at the center of the atom. -
Neils Bohr
stated that the electrons moved around the nucleus in successively large orbits. He also presented the Bohr atomic model which stated that atoms absorb or emit radiation only when the electrons abruptly jump between allowed, or stationary, states. -
Electron Cloud
Electron clouds are created when accelerated charged particles disturb stray electrons already floating in the tube, and bounce or slingshot the electrons into the wall. These stray electrons can be photo-electrons from synchrotron radiation or electrons from ionized gas molecules. When an electron hits the wall, the wall emits more electrons due to secondary emission. These electrons in turn hit another wall, releasing more and more electrons into the accelerator chamber. -
Erwin Shroedinger
introduced the Shroedinger Equation, a wave equation that describes the form of the probability waves that govern the motion of small particles and how these waves are altered by external influences.
