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460 B.C: Greek philosopher Democritus began to develop the idea of a atom
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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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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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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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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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1905: Einstien wrote a paper that explained that light absorbtion can release electrons from atoms, calling it the 'photoelectric effect'.
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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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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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1921: Einstien recieves a nobel prize for physics for his work on the photoelectric effect.
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1924: Pauli, an Australian physicist predicted that the elecrton should spin on an orbit while travelling around the nucleus.
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1932: Chadwick discovered the neutron.
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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.