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Democritus(460-370 B.C) First person to suggest that matter could not be infinitely divided.
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Aristotle (384-322 B.C) Disagreed with Democritus' idea that atoms move through empty space. His ideas about matter took over those of Democritus- back to square one.
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John Dalton (1776- 1844) English schoolteacher who marks the beginning of the developement of modern atomic theory. Took Democritus' ideas about matter and revised them based off of his personal scientific research.
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Conseravtion of Mass (490-430 B.C) Atoms can rearranged, seperated, or combined to form new things, but cannot be created, destroyed, or divided in the process.
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The Atom (1800s) Since the adoption of Dalton's atomic theory, the existence of atoms has been scientifically proven.
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The Cathode Ray Tube (1869). Matter and electric charge must be related. Glass tubes with air removed from the inside chamber connected to an electric source via a cathode and an anode.
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J.J Thompson(1856-1940) designed a series of CRT experiments at Cambridge to find the ratio of the partices to change the mass.Thompson received the nobel prize in 1906 for his research- discovery of the electron, the first subatomic particle.
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Physicist Robert Millikan (1868-1953) designed an oil drop apparatus to determine the charge of the electron.
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Ernest Rutherford studied how positvely charged a-particles interacted with solid matter. He designed an experiment to see if a-particles would be deflected as they passed through a thin sheet of gold.
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BAsed on the results of his gold foil experiment, Rutherford calculated that an atom was mostly just empty space for electrons to move around it. There hadto be a place for the positive charge and the majority of the mass of an atom to reside. He claimed that it was contained in a tiny region in the center of the atom. That spot was called the nucleus.
