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Stated that matter is made of indivisible, solid particle called atoms.
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Proposed an Atomic Theory in which atoms are based upon measurable properties of mass.
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Discovered a trend in certain groups of elements, for example, the average atomic mass of lithium and potassium was close to the atomic mass of sodium. A similar pattern was found with calcium, strontium, and barium, with sulfur, selenium, and tellurium, and also with chlorine, bromine, and iodine. Moreover, the densities for some of these triads followed a similar pattern.
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Drew the first periodic table of chemical elements
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First person to devise a Periodic Table of Elements based upon atomic weight, and also published the Law of Octaves. This law states that any given element will exhibit analouge behavior to the eighth element following it in the table.
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Created the Periodic Law stating that properties of elements "were periodic functions of their atomic weights."
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Crooks discovered that cathode rays travel in straight lines from the cathode, cause glass to fluoresce, impart a negative charge to objects they strike, are deflected by electric fields and magnets to suggest a negative charge, and cause pinwheels in their path to spin indicating they have mass. Ultimately, he created the Cathode Ray Tube, formerly known as the Crooks Tube.
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Using a CRT he observed that nearby chemicals glowed. Further experiments found very penetrating rays coming from the CRT that were not deflected by a magnetic field. He named them "X-rays".
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Discovered the electron using the Cathode Ray Tube. He discovered that the electron has a negative charge, but that the atom had no charge, meaning there must also be a positive component to the atom. This was the creation of the plum pudding model.
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Published the theory E=mc^2
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Deceloped a device that would click every time an alpha particle hit it.
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Ran the gold foil experiment, and found that every 1 out of 8000 rays of light was deflected nearly streaight back. This was the discovery of the nucleus. He concluded that the nucleus had a positive charge.
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Bohr developed an explaination of atomic structure. The atomic model that resulted is made up of successive shells of electrons.
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Viewed electrons as continuous clouds, and showed wave mechanics as a mathematical model.
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These two men were the first to synthesize Bose-Einstein condensate, a substance that displays quantum mechanical properties in macroscopic amounts.
