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19 Cards in this Set
- Front
- Back
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atom
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the smallest particle of an element that can exist either alone or in combination with other atoms
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democritus
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first to suggest the idea of an atom
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DEMOCRITUS ATOM theory
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identical in substance
different sizes and shapes in constant motion indivisible and eternal |
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John Daltons Atomic theory 1(1808)
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- all matter is composed of extremely small particles called atoms
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J D A T 2
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-atoms of a given element are identical in Size MAss and other properties, atoms of different elements DIFFER in size mass and other properties
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J D A T 3
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Atoms cannot be subdivided, created, or destroyed
A+B= AB |
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J D A T 4
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Atoms of different elemts can combine in simple whole number ratios to form chemical compounds ( law of deefinite composition)
2Hs+0s --> 2HsO |
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J D A T 5
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in chemical reactions, atoms are combined, separated, or rearranged
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Atomic structure
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the identity and arrangement of smaller particles within atoms
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electrons
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negatively charged subatomic particles
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Thompson 1897
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identified electron using cathode ray experiment
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melikah 1909
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calculated mass of electron and determined the charge as being -1.
mass- 9.109 X 10 to the -28 |
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nucleus
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positively charged dense central portion of the atom that contains nearly all of its mass but takes up only an insignificant fraction of its volume
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Rutherford, Geiger, and Marsden 1908 1909
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used gold foil experiments to discover nucleus
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proton
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subatomis particles that have a positive charge equal in magnitude to the negative charge of an electron and are present in atomic nuclei
mass- 1.673 X 10 to -24 rel mass. 1 amu... charge +1 |
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Rutherford 1919
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discovered protons ** same number of protons and electron
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neutrons n to the o
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electrically neutral, subatomic particles found in atomic nuclei
mass 1.675 X 10^-24 charge 0 neutral rel mass - 1 amu |
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chadwick 1932
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discovered neutron
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element
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a substance composed of atoms all of which contain the same # of protons
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