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400 BCE
Democritus
Democritus concluded that if you divided something in half, both halves would have the same properties as the whole. He also concluded that there would be a point where it would become indivible. He called those "atomos" which is Greek for indivible -
John Dalton
John Dalton invents an atomic theory based off Democritus's.- Elements are made up of tiny particles called atoms
- Atoms of one element are identical, while atoms of different elements are different. 3.
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J.J. Thomson
He concluded that atoms had negative particles. He concluded that by using a cathode ray. He put gas into a vacuum sealed glass tube, and when a charge was emitted, the light went from the negative end towards the positive end and glowed. -
Robert Millikan
He measured the charge of an electron using oil droplets. He compared the electric force with the motion of the oil drop. -
Niels Bohr
He concluded that electrons are orbiting the nucleus, which answered alot of questions about how atoms worked before then. -
Ernest Rutherford
He concluded that most of the atom was empty space. He shot alpha hydrogen particles at gold foil. The atoms then bounced off the foil, but most of them went through the foil. So he realized there must be lots of space in-between atoms. He would also name the proton, and discover the existence of a neutron. -
Erwin Schrodinger
He theorized that electrons could be particles and waves, that can be used to find the energy level of an atom.