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Atomic Theory

By whatleyheather453
  • 442 BCE

    Thinking About Matter

    Thinking About Matter
    Democritus, a Greek philosopher, and his teacher originated the thought that all matter is composed of indivisible elements.

  • John Dalton and Atoms

    John Dalton and Atoms
    John Dalton, developed a theory that matter is simply composed of atoms. He also proposed that these atoms are spherical, and are in motion.

  • Radiation, Energy, and the Atom

    Radiation, Energy, and the Atom
    Pierre and Marie Curie theorized that radioactive particles cause atoms to break down, then releasing radiation that takes the form of energy and subatomic particles.

  • Electrons discovered

    Electrons discovered
    JJ Thomson discovers the electron, using properties of cathode rays.

  • Structure of an Atom Developed

    Structure of an Atom Developed
    Ernest Rutherford (known as the father of nuclear physics), developed the theory for the structure of the atom. He used a gold foil experiment, observing the scattering of alpha particles, and demonstrated for the first time the existence of the atomic nucleus.

  • Bohr Improves the Atomic Model

    Bohr Improves the Atomic Model
    Neils Bohr developed the Bohr atomic model, with electrons travelling in orbits around the nucleus, and chemical properties being determined by how many electrons are in the outer orbits.