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440 BCE
Democritus
said matter was composed of tiny particles gave them the name A tomos:uncuttable or indivisible -
Dalton
All matter was composed of atoms. Different elements had atoms differing size and mass. -
Thompson
founded the electron. Positively packed spheres with negativity charged electrons. -
Rutherford
Atoms consisted largely of empty space while most of the mass focused in the center and called the nucleus -
Bohr
- Found electrons orbited the nucleus. Electrons jumped from one ring to another but never in the space in between.