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A Greek plilosopher originated the though that matter is composed of invisible elements
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John developed a theory that all matter is composed of different atoms of different weights and is combined in ratios by weight. He also said atoms are spherical and in motion.
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Theorized that radioactive particles cause atoms to break down
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JJ discovered electrons using properties of cathode rays
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Stated that electromagnetic energy could only be emitted in quantized form. (His quanta is now called photons)
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Suggests that the atom has acentral nucleus
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Robert measured the charge of a single electron
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Developed a theory for the structure of an atom, he used a gold foil experiment to help him look at the scattering of alhpa particles, he was the first to demonstrate the atomic nucleus existence
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Neil developed the Bohr atomic model which stated that electrons are trveling in orbit around the nucleus
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Proposes that moving particles like electrons, have some properties of waves
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He described how electrons move in a wave form
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described atoms by means of formula connected to frequencies of spectrical lines
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Proposed Anti-particles
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Discovers the nuetron component of the atomic nucleus
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Processes the Quark model and describes elementary particles that have no substructure