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History of the atom

  • Period: 460 to 470

    The beginning

    460 B.C: Greek philosopher Democritus began to develop the idea of a atom
  • Period: Jan 1, 600 to Jan 2, 600

    Before the atom

    600 B.C: theroies of electricity began as Thales of Miletus discovered that after rubbing a piece of amber with fur, it attracts bits of hair, feather and other light objects.
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    John Dalton

    Early 1800's: John Dalton conducted a experiment using various chemicals , demonstrating that matter seems to consist of elementary lumpy particles (now known as atoms)
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    J.J Thompson

    1897: English physicist J.J Thompson discovered the electron and announced the model for the structure of an atom. He knew that electrons had a negative charged and thought that matter must have a positive charge.
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    Max Planck and Albert Einstien

    1900: Max Planck (a professor of theoretical physics) proclaimed that when you vibrate atoms strong enough, you can measure the energy in discrete units. He called these enery packets, quanta. Many physicists at the time thought light consisted of waves. Albert Einstien though believed that quanta behaved like discrete particles. Physicists called this discrete light particle of Einstien's a photon
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    Albert Einstien

    1905: Einstien wrote a paper that explained that light absorbtion can release electrons from atoms, calling it the 'photoelectric effect'.
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    Ernest Rutherford

    1911: Rutherford thought it would be interesting to bombard atoms with alpha rays, thinking the experiment could investigate the inside of an atom. The results of this experiment were unexpected as most of the alpha particles ran smoothly through the foil. Only some particles turned away sharply from its original path.
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    Neil Bohr

    1912: Bohr created a theory and some rules to describe the way an atom work. These rules are: RULE 1: Electrons can orbit only at certain allowed distances from the nucleus. RULE 2: Atoms radiate energy when an electron jumps from a higher-energy orbit to a lower-energy orbit. Also, an atom absorbs energy when an electron gets boosted from a low-energy orbit to a high-energy orbit.
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    Nobel prize

    1921: Einstien recieves a nobel prize for physics for his work on the photoelectric effect.
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    Wolfgang Pauli

    1924: Pauli, an Australian physicist predicted that the elecrton should spin on an orbit while travelling around the nucleus.
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    James Chadwick

    1932: Chadwick discovered the neutron.
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    Murray Gell-Mann and Yuval Ne'man

    1960: Gell-Mann and Ne'man independently proposed a method for classifying all particles known at the time. This method was known as the Eightfold Way. What the periodic table did for elements, the Eightfold Way did for particles.