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Atomic Atom History

By Nick Tharp
  • 460 BCE

    Democritus

    Democritus
    Democritus' experiment was him just simply saying atoms were the building blocks of everything. His contribution to the atom was his atomic theory. Which stated everything is made up of two elements, atoms and the void in which they exist and move

  • John Dalton

    John Dalton
    In John Daltons experiment he observed the pressure of steam at various points in temperatures between 0 and 100 degrees Celcius. John Daltons contribution added on to the atomic theory saying all matter was composed of atoms. But added that while all atoms of an element were identical, different elements had different atoms of differing size and mass.

  • JJ Thompson

    JJ Thompson
    Over the course of three experiments J. J. Thomson discovered the existence of electrons. He did this using a cathode ray tube, which is a vacuum-sealed tube with a cathode and anode on one end that creates a beam of electrons travelling towards the other end of the tube. The contribution Thompson made was by doing his cathrobe tube experiment he discovered electrons, which have a negative charge. He also discovered minor positive particles in neon gas.

  • Ernest Rutherford

    Ernest Rutherford
    Physicist Ernest Rutherford established the nuclear theory of the atom with his gold-foil experiment. When he shot a beam of alpha particles at a sheet of gold foil, a few of the particles were deflected. He concluded that a tiny, dense nucleus was causing the deflections. Rutherford contributed that when he did his experiment in 1911, atoms have a small charged nucleus surrounded by large empty space and it is circled by tiny electrons. This is known as Rutherford model.

  • Niels Bohr

    Niels Bohr
    Niels Bohr experiment was called the Bohr model. In Bohrs model he depicts the atom as a small, positively charged nucleus surrounded by electrons that travel in circular orbits around the nucleus—similar in structure to the solar system, but with attraction provided by electrostatic forces rather than gravity. His contribution to the atom was is that in 1913, proposed a theory for the hydrogen atom based on quantum theory that energy is transferred only in certain well defined quantities.