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Made the atomic theory. He said that everything was made up of small particles called atoms
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Proposed the atomic theory.
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his “law of octaves” noted a pattern in the atomic structure of elements with similar chemical properties and contributed in a significant way to the development of the periodic table.
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discovered the element thallium and made special studies of radioactive substances in the course of which he invented the crookes tube,
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His first Periodic Table was compiled on the basis of arranging the elements in ascending order of atomic weight and grouping them by similarity of properties.
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Descovered the electron. To support this he made the "Plum Pudding" model
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He suggested that the outer orbits could hold more electrons than the inner ones, and that these outer orbits determine the atom's chemical properties.
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discovered the existance of neutrons. His therory was that it had a reppeling effect to protons, keeping the nuclei together. He made an atomic model to support it
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Chadwick had created an experiment to answer the question of the unknown nucleus mass source, thus discovering the neutron.
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Aristotle said there were only four elements (earth, air, fire, water) and that these had some smallest unit that made up all matter.
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