Atomic History.docx - Atomic History Democritus(400 B.C.E...

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Atomic History Democritus (400 B.C.E) Indivisible- “Atomos”- Greek Atom John Dalton (1803) - Came up with all elements are made up of atoms - Believed atoms of the same element are identical (not true today) o Isotopes - Believed atoms of different elements are different - Believed atoms combine in whole number ratios to form compounds - Believed atoms are not created or destroyed during chemical reactions J.J. Thomson (1897) - discovery of electron - negative is raisins/ positive is pudding - plum pudding Ernest Rutherford (1903) – student of J.J. Thomson - Gold foil experiment - Alpha particle (positively charged) 7200 x mass of an electron - Mush of electrons Neils Bohr (late 1900’s) Planetary – the earth has enough energy in its orbit to stay away from the sun
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  • Fall '14
  • Arleth
  • Atom, Ernest Rutherford, Neils Bohr, J.J. Thomson, Lamda

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