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The Greek mathematician suggested that all matter was constructed of invisible indestructible particles called atoms that were not all identical and moves randomly about in a void.
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He theorised a mechanical universe with small, solid masses in motion
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He proposed that all matter consists of tiny particles called atoms that cannot be divided into smaller particles. The atoms of each element were different to one another because they had the different mass and atoms combined in simple whole number ratios.
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Stoney theorised that electricity was comprised of negatively charged particles he called electrons.
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He proposed a model where atoms were positively charged spheres with negatively charged electrons embedded within. He discovered electrons in his experiments of electric discharge in a high-vacuum cathode-ray tube.
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Suggested the theory of quanta. He observed light emitted from hot, glowing objects.
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Proposed a ‘Saturnian model’ of the atom where negative electrons orbit the positive nucleus in flat rings.
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His ‘oil drop experiment’ determined the mass and the charge of electrons.
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His famous experiment where most radioactive alpha particles that were fired at a thin sheet of gold passed straight through proved that atoms were mostly empty space with a small, dense nucleus containing positive protons and negatively charged electrons orbited the nucleus.
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He studied X-rays given off by various elements that gave off their own distinct wavelengths which could determined that the atomic number is equal to the number of protons in an atom.
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He suggested that electrons orbited the nucleus at different energy levels (shells). Only electrons with a specific amount of energy could be found in each shell.
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Chadwick found neutral atomic particles similar in mass to protons using alpha particles. These were found in the nucleus and were named neutrons.