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400
Democritus
he believed that that the atoms was unbreakable into smaller parts. He conduct a simple experiment were he took small pieces and tried to crush the big pieces up smaller ; thats when he came up with atoms. -
Dalton
He learned that it was not a chemical solvent,instead it was a mechanical system composed of small indivisual particals. Gas led him to his discovery that thee total pressure of a mixture of gas amounted to the sum of the portial pressures that each indivisual gas exerted while occupying the same space. -
Thomas
Thomson interpreted the deflection of the rays by electrically charged plates and magnets as evidence of “bodies much smaller than atoms” that he calculated as having a very large value for the charge-to-mass ratio.Thomson suggested a model of the atom as a sphere of positive matter in which electrons are positioned by electrostatic forces -
Rutherford
He discovered the conncept of nucleus in atoms.He thought that atoms were negativity charged; since there were negative particles there must be positive to, to make it neutral. -
Bohr
Electrons travel in separate orbits around the nucleus and that the number of electrons in the outer orbits determines the properties of an element. He came up of his dicovery using the liquid droplet theory. Also, he say they came in 2 ways, either as particles or as a wave, but never both at the same time. -
Heisenberg and Schrodinger
You cannot know by measuring the position and movement of a particle simuleously; but with a microscope. Atoms were now visable as a nucleous surrounded by cloud of electrons in a wave pattern.
