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