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34 Cards in this Set
- Front
- Back
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Believed matter was made up of small spheres
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John Dalton
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Believed atoms had no change
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John Dalton
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Expirementally discovered atoms
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John Dalton
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Believed in indivisble pieces called atoms
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John Dalton
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Made discoveries in 1803
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John Dalton
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Believed the world is made up of two things: empty space and atomos
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Democritus
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Believed individual atoms did not exist
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Aristotle
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Believed there were five elements: fire, water, earth, air and ether (empty space)
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Aristotle
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Attempted to make gold out of ordinary elements
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Alchemists
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First unofficial chemists
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Alchemists
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Expiremented with different elements and reactions
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Alchemists
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The Law of Definite Proportions: the ratio of two or more elements in a compound never change
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John Dalton
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The Law of Multiple proportions: the raito of masses of elements combined together can be expressed in whole numbers
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John Dalton
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The Law of Conservation of Mass: Matter can be altered but never created of destroyed
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John Dalton
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Believed atoms are made up of charged particles
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JJ Thomson
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Used a cathode ray tube to generate a stream of electrons, he used an electrical field to bend the stram of electrons
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JJ Thomson
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Plum Pudding Model: Negative electrons embedded in a positive sphere
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JJ Thomson
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Conducted oil drop expirement to determine magnitude of the electron charge. ONe electron = 9.11 x 10^-31 kg
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Robert Milikan
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Found the nucleus and determined it was positively charged, very dense and made up most of the mass
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Lord Rutherford
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Determined atoms were made up of mostly empty space
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Lord Rutherford
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Found that some particles bounced off of something in the atoms
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Lord Rutherford
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Discovered high energy particles with no charge in nucleus (neutrons)
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James Chadwick
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Expiremental difference in mass of an atom and the number of protons
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James Chadwick
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Found that electrons must move in concentric circles (orbits) around the nucleus
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Niels Bohr
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Distinct Energy Levels:
1st Layer - 2 electrons 2nd Layer - 8 electrons 3rd Layer - 18 electrons 4th Layer - 32 electrons |
Niels Bohr
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1913
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Niels Bohr
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1932
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James Chadwick
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1909
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Lord Rutherford
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1899
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Robert Milikan
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1897
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JJ Thomson
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1803
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John Dalton
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300- 1400 AD
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Alchemists
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382 - 322 BC
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Aristotle
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400 BC
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Democritus
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