Atomic Theory

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Meaning of "Atomos"

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Uncuttable

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Democritus's Contribution

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Proposed the idea of indivisible matter.

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Greek Philosopher in Atomic Theory

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Democritus

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Image of Democritus

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Illustration of Democritus, a key figure in atomic theory.

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Name for negatively charged particles discovered by Thomson

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Electrons (Thomson called them corpuscles).

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Thomson's proposal for atomic neutrality

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Atoms must also have a positive charge to make the atom neutral.

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Fixed orbit in Bohr's model

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In Bohr's model, each electron is in a fixed orbit, also known as an energy level.

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Identity of an atom

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Determined by the number of protons it has.

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Location of protons in an atom

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Located in the atom’s nucleus.

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Contribution of protons to an atom

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Protons contribute mass to the atom.