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500 BCE
Start of timeline
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Period: 500 BCE to 400 BCE
Democritus proposed the existance of atoms
Limited technology at the time meant this was just an idea and could not be tested. -
Delton developed his theory of atoms and matter
Experiments in chemistry and careful measurement of results allowed Dalton to support his hypotheses with evidence. -
J. Thomson discovered the electron
Experiment using electric charges in cathode ray tubes -
Rutherford developed the planetary model of the atom
Experiment using alpha particles fired at thin gold foil and an early prototype "Geiger counter" to measure results. -
Bohr developed a model of the atom: Bohr's Model
Bohr used mathematical models and laws of quantum physics to propose his updated model. -
The neutron was discovered by James Chadwick
Experiments using kinematics and accurate measurements lead to proving the existence of a previously undetected subatomic particle, the neutron. -
End of timeline