The Atom

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Democritus

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A Greek philosopher who was first to propose the idea that atoms exist.

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Aristotle

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A Greek philosopher that rejected Democritus's idea that atoms exist.

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John Dalton

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Revived and revised Democritus's ideas about the atom based on scientific research to propose Dalton's Atomic Theory in 1803.

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William Crookes

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Discovered the cathode ray while studying how electricity behaves in vacuum tubes. Developed the Crookes tube for these experiments.

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JJ Thomson

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Identified the first subatomic particle, the electron, using cathode rays.

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Ernest Rutherford

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In 1911, performed the gold-foil experiment and discovered the nucleus of the atom.

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James Chadwick

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In 1932, showed that the nucleus also contained a neutral particle called the neutron.

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Plum Pudding Atomic Model

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Proposed by Thomson, showed that negatively charged electrons were distributed throughout a uniform positive charge.

Front

Rutherford's Nuclear Atom

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Shows the concentrated positive charge in the nucleus at the center of the atom and surrounded by negatively charged electrons.

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Atom

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The smallest particle of an element that retains the properties of the element.