-
685 BCE
685 AD
-
440 BCE
Democritus
Atoms are uncuttable. -
315 BCE
315 BCE
-
190 BCE
190 BCE
-
65 BCE
65 BCE
-
60
60 AD
-
185
185 AD
-
310
310 AD
-
435
435 AD
-
560
560 AD
-
Jan 1, 810
810 AD
-
Jan 1, 935
935 AD
-
Jan 1, 1060
1060 AD
-
Jan 1, 1185
1185 AD
-
Jan 1, 1310
1310 AD
-
Jan 1, 1435
1435 AD
-
Jan 1, 1560
1560 AD
-
1685 AD
-
John Dalton
-Atoms of different elements are different
-He conducted experiments in combining elements
-Atoms of the same element are exactly alike
-All substances are made of atoms
-He wanted to know why elements combine in specific proportions -
1810 AD
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JJ Thompson
-There are small, negatively charged particles inside an atom
-He conducted the cathode-ray tube experiment
-His theory of the atomic structure led to the plum-pudding model -
Rutherford
-Most of the mass of an atom's mass is in the nucleus
-There are small, negatively charged particles inside an atom
-Atoms contain mostly empty space
-His model had electrons surrounding the nucleus at a distance
-He conducted the gold-foil experiment -
Bohr
-Electrons can jump from a path in one level to a path in another level
-Electrons travel in certain paths, or energy levels -
Schrodinger and Heisenberg
-Electron paths cannot be predicted
-Electrons are found in electron clouds not paths -
1935 AD
-
2060 AD
