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400 BCE
Democritus
Democritus discovered that, atoms are small, hard particles, atoms constantly move and atoms are not able to be cut -
400 BCE
Democritus Atom Model
This what was believed to be an atom during Democritus's time -
John Dalton
Dalton discovered that all substances are made of atoms
Atoms of different elements are different
Atoms of the same element are exactly alike
Elements combine in specific proportions. Dalton also
conducted experiments in combining atoms -
John Dalton Atom Model
This is what was believed to be an atom during Dalton's time -
J.J. Thomson
Thompson's theory of the atomic structure lead to the "plum pudding" model and that there are small negatively charged particles inside an atom. Thompson conducted the cathode-ray tube experiment -
J.J. Thomson
This is what was believed to be an atom during Thomson's time -
Ernest Rutherford
Rutherford discovered that, atoms contain mostly empty space, electrons move in empty space in the atom, most of an atom's mass is the nucleus, there is small, dense, positively charged nucleus -
Ernest Rutherford Atomic Model
This is what was believed to be an atom during Rutherford's time -
Niels Bohr
Bohr discovered that electrons jump between levels from path to path and that electrons travel in definite paths. -
Niels Bohr Atomic Model
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Schrodinger and Heisenberg Atom model
This is what was believed to be an atom at the time -
Erwin Schrodinger and Werner Heisenberg
Schrodinger discovered that electron paths can not be predicted and both Erwin and Werner had discovered that electrons are found in clouds and not paths
