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450
DEMOCRITUS (450 BC)
Democritus wondered how many times an individual could split a piece of matter until it could no longer be split in half. He concluded that this last stage is called an atom. He found this information by questioning the world he new and using reason, as opposed to an experiment. He did not have an atomic model.
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450
ARISTOTLE (BC Era)
Aristotle dismissed the concept of an atom even existing. Because he was so revered among the people of his time, his opinion caused others to also not believe Democritus' idea.
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DALTON
Dalton believed that matter consists of individual atoms and that these atoms arrange in different combinations to make different components. He used an expriment that showed that matter indeed consisted of atoms.
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THOMSON
Thomson claimed that electrons were negative, protons were positive, and electrons in regards to an atom look like "raisins in pudding" , the pudding being the positve matter, protons.
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Period: to
RUTHERFORD
He discovered that atoms had a nucleus and that these necleis contain positively charged particles called protons. He discovered this using the Gold Foil experiment which is when he shot alpha particles at gold foil and see how the particle moved through the molecules of the foil.
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BOHR
Bohr the following rules after multiple experiments in regards to the behavior of electrons:
1) Electrons can only orbit a certain distance away from the nucleus.
2) Atoms radiate energy when an electron jumps from a higher-energy orbit to a lower-energy orbit. Also, an atom absorbs energy when an electron gets boosted from a low-energy orbit to a high-energy orbit.
Later, exceptions were developed in the cases of heavier atoms and atoms effected by strong magnetic fields.
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HEISENBURG AND SCHRODINGER
They discovered that electrons moved sporadically, like crazy flies, rather than a set orbit around the nucleus. The scientists used a mathmatical equation that desribed the variables on how electrons moved.
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