Atoms are solid and same throught.Universe consisted of empty space and atoms (atomos).Thought atoms were indivisible.
Democritus
John Dalton
Matter is made of atoms.Atoms Cannot be destroyed or made.
J.J Thomson
Dicovered that atoms have charges. The plum pudding model showed floating electorns.Modified Dalton's idea atom ( no longer solid).
Ernest Rutherford
Tested Plum Pudding model.Shot tiny positivly charged particles out of particle gun into gold foil.Determined from expirements and clues that electrons must orbit some distance from center.
Used expiremental data from emission or discharge and absorbsion spectra elements to shape the his theory.Believed electrons occupy specific or exact ,energy levels.Energy levels are specific distances from nucleus.
Neils Bohr
Modeled wave equation that allowed scientists to identify properties of electrons as both a wave and particle.Believed that electrons dont stay in a certain orbit,but can have a predicted zone around nucleus(electron cloud).