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Proposed Billard Ball model atom is a uniform solid sphere.
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Proposed ‘Plum Pudding’ model – atom has a positive sphere (pudding) with negative electrons (plums) dispersed throughout.
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Discovered nucleus of atoms. Proposed ‘Nuclear’ model – atom has dense, positive nucleus surrounded by negative electrons.
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Proposed ‘Planetary’ model – atom has electrons that move in circular orbits within specific energy levels.
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Revised ‘Nuclear’ model – atom has a neutral particles in the nucleus (neutrons).
