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10 Cards in this Set
- Front
- Back
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Democritus
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Greek Philosopher 460-370 BC
Proposed the existence of atoms He said that atoms were small particles that varied in shape and size |
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John Dalton
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PROPOSED ATOMIC THEORY 1808
+ atoms were a tiny hard sphere |
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Joseph John Thomson
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1868 - made observations with cathode ray tube. identified the electron. said that the nucleus has electrons embedded in it to give charge. cookie dough model.
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Ernest Rutherford
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1911 - gold foil experiment. deferred that atoms made of mostly empty space. positively charged nucleus electrons surrounded nucleus. said that nucleus held majority of mass.
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Niels Bohr
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1885-1962 - said that the electons moved around the nucleus in fixed orbits with a fixed amount of energy.
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Erwin Schrodinger
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1926 - developed a mathematical description of electrons (Quantum Mechanical Model || Electron Model) cloud used to represent probability of electron placement
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James Chadwick
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1932 - discovered the neutron
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ATOMIC THEORY
proposed by whom? who gathered evidence for it? what year did he publish it? |
ppd by greeks in 400 BC
John Dalton collected evidence published it in 1808 |
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ATOMIC THEORY
pts one through three |
1. all elements are composed of extremely small particles (atoms)
2. all atoms of a given element are identical. 3. atoms of different elements have different properties |
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ATOMIC THEORY
pts 4 through six |
4. atoms are only rearranged in chemical reactions, not changed
5. compounds are formed when atoms of one or more elements combine 6. a compound is defined by the number type and proportion of the constituent atoms |
