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In the early 1800's, John Dalton preformed experiments with chemicals to confirm that matter was made of elementary particles.
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In 1897, JJ Thompson discovered electrons, which he knew had a negative charge. He then knew that the matter had to have a positive charge. His model is said to have looked like a lump of pudding with raisins stuck in, hence it's title.
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In 1911, Ernest Rutherford used Radium to probe the atom to see what the inside was like. He shinned the Radium particles onto the atoms in gold foil with a flourescent screen behind them that he observed through. He found that most of the particles went through the foil. He found that this must mean that...
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they must get scattered around by positively charger matter and that the space around the positively charged matter was mostly empty, and that that must be where the electrons reside, orbiting it like the sun and planets.
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In 1912, Niels Bohr theorized that electrons don't spiral INTO the nuclean and came up with rules that show what DOES happen.
Rule 1: Electrons only obrit a certain distance from the nucleus.
Rule 2: Atoms release energy when an electron moves from a higher- to lower-energy orbit abd they absorb energy when an electron moves from a lower- to a higher-energy orbit. -
In 1926, Erwin Schrödinger came up with a question: Why not go all the way with particle waves and try to form a model of the atom on that basis? This theory worked like harmonic theory for a violin string, but instead, the vibrations traveled in circles. Schrödinger's wave mechanics needed a name, so he gave it the symbol 'psi', which comes from the Greek alphabet.
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