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400 BCE
Democritus
Used his sense and logic to reason that there must be something universal making up everything. First person to suggest the idea of an atom. -
400 BCE
Picture of Democritus
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John Dalton
Used gas experiments to reinforce the ideas that Democritus suggested. However, Dalton was able to prove these idea in his experiments. He also created five laws of atoms, some of which still apply to modern day science -
John Dalton Experiment
Little knowledge on experiment, however this is how people thought he did it. -
John Dalton Picture
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JJ Thomson
Used Cathode ray experiment which consisted of two charged plates in the center, to figure out that atoms have charges which lead him to discover the electron. This theory came from a result of seeing that atoms ionized as they were drawn to the charge. He created the plum pudding model -
JJ Thomson Experiment
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JJ Thomson Picture
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Ernest Rutherford experiment
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Ernest Rutherford Picture
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Ernest Rutherford
Created the gold foil experiment which tested alpha particles on a piece of gold foil. He discovered that some of the alpha particles appeared on the other side of the the gold foil which lead him to discover the dense nucleus in the center of the atom. -
Neils Bohr
Neils Bohr made important contributions to the atomic model including explaining why element changed color when exposed to high amount of energy. Because of this he introduced the idea of multiple energy levels on different electron orbits. He also introduced the idea of how electrons perform a quantum jump when they receive more or less energy. -
Bohr model
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Quantum mechanical model
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Erwin Schrödinger’s
Erwin was a physicist who made his contribution to the atomic model by explaining why Bohr's model was faulty and how to improve on it. The Bohr model was built on mathematical thinking, however the math only proved valid for the atom of hydrogen. Erwin explained that this was because electrons aren't on a fixed orbit like planets are, they move around in various places and ways. He demonstrated this in his model by making areas where the electrons are probable to be at but not certain.
