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440 BCE
Democritus
Atoms are "uncuttable." -
440 BCE
Democritus
Atomic model. -
440 BCE
Democritus
Atoms are small, hard particles. -
440 BCE
Democritus
Atoms constantly move. -
Period: 440 BCE to
Atomic Theory
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John Dalton
Atoms of different elements are different. -
John Dalton
Atoms of the same element are exactly alike. -
John Dalton
All substances are made of atoms. -
John Dalton
Elements combine in specific proportions. -
John Dalton
He conducted experiments in combining elements. -
J.J. Thomson
His theory of the atomic structure lead to the "plum-pudding" model. -
J.J. Thomson
He conducted the cathode-ray tube experiment. -
J.J. Thomson
There are small, negatively charged particles inside an atom. -
Ernest Rutherford
Atoms contain mostly empty space. -
Ernest Rutherford
Electrons move in empty space in the atom -
Ernest Rutherford
Most of an atom's mass is in the nucleus. -
Ernest Rutherford
There is a small, dense, positively charged nucleus. -
Ernest Rutherford
He conducted the gold foil experiment. -
Niels Bohr
Electrons jump between levels from path to path. -
Niels Bohr
Electrons travel in definite paths. -
Erwin Schrodinger
Electron paths cannot be predicted. -
Erwin Schrodinger and Werner Heisenberg
Electrons are found in electron clouds, not paths.
