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timeline of the atomic theory

  • 400 BCE

    democritus

    He developed the concept of an atom. Discovered everything is made up of an atom.
  • Lavoisier

    The law of conversion of mass. He discovered that mass can't be destroyed in chemical reactions.
  • John dalton

    The theory of atomism. He developed methods to calculate atomic weight. He formulated the law of partial pressures.
  • Mendeleev

    He formulated the periodic law and made the periodic table.
  • j.j thomson

    He discovered the electron and went on to propose a model for the structure of an atom. His work led to the invention of the mass spectrograph.
  • millikan

    He discovered the elementary charge. He used the oil drop experiment.
  • Ernest Rutherford

    He discovered the nuclear structure of an atom. He also discovered alpha and beta rays, and proposed the laws of radioactive decay.
  • Bohr

    He proposed the theory of the hydrogen atom. He made a model of the atom called the Bohr model.
  • Chadwick

    He discovered the neutron