-
440 BCE
Democritus
-
440 BCE
Democritus
atoms are "uncuttable."
atoms constantly move
atoms are small, hard particles -
John Dalton
-
John Dalton
all substances are made of atoms
atoms of different elements are different
atoms of the same element are exactly alike
he conducted experiments in combining elements -
J.J. Thomson
-
J.J. Thomas
he conducted the cathode-ray tube experiment
his theory of the atomic structure lead to the "plum pudding" model
there are small, negatively charged particles inside an atom -
Ernest Rutherford
-
Ernest Rutherford
atoms contain mostly empty space
he conducted the golf foil experiment
most of an atom's mass is in the nucleus
there is a small, dense positively charged nucleus -
Niels Bohr
-
Niels Bohr
Electrons jump between levels from path to path
electrons travel in definite paths -
Erwin Schrodinger & Werner Heisenberg
-
Erwin Schrodinger & Werner Heisenberg
electron paths cannot be predicted
electrons move in empty space in the atom
electrons are found in electron clouds, not paths
