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10 Cards in this Set
- Front
- Back
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Democritus hypothesis? - Atomos - Not accepted by whom... -Endured until when... |
All mass consists of very small invisible particles -Greek name for uncuttable or indivisible -Not accepted by Aristotle or Plato -Endured until early 1800`s when chemistry really started |
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Daltons Atomic Theory (1st hypothesis) Daltons Atomic Theory (2nd hypothesis) |
1) Elements consists of extremely small particles; atoms 2) All atoms of an element are identical -same size, mass, chemical properties -atoms of one element are different from atoms of all other elements |
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Dalton`s Atomic Theory 1st and 2nd hypothesis - Dalton did not describe the ... |
- Did not describe the structure or composition of an atom - He had not idea what it was like - He realized if elements had different properties, this could be explained if their atoms were different Example: hydrogen and oxygen behave differently |
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Daltons atomic theory (3rd hypothesis) |
- compound consist of atoms of more than one element - In any compound, the ratio of the number of atoms in any 2 of the elements present is either an integer or simple fraction |
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Examples of Dalton`s 3rd hypothesis |
- Water is represent by H20 -Ratio of the number of hydrogen atoms to the number of oxygen atoms= 2 - ratio of number of oxygen atoms to hydrogen atoms = 1/2 -Chalk is represented by CaCO3 -ratio of the number of oxygen atoms to the number of calcium or carbon atoms = 3 -Ratio of the number of calcium or carbon atoms to the number of oxygen atoms = 1/3 |
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Daltons Atomic Theory 3rd hypothesis - Extension of the law of definite proportions (proust) |
- Different samples of the same compound always contain its constituent elements in the same proportion by mass - Analysis of different samples of CO2 from different sources have same ratio by mass of carbon to oxygen |
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Daltons Atomic Theory 3rd hypothesis - Supports the law of multiple proportions |
- If two elements combine to form more than 1 compound, the masses of 1 element that combine with a fixed mass of the other element are in ratios of small whole numbers
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Examples of the law of multiple proportions |
- Carbon forms two stable compounds with oxygen carbon monoxide: CO carbon dioxide: CO2 ratio of oxygen in CO to oxygen in CO2 = 1:2 |
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Dalton`s atomic theory 4th hypothesis |
- a chemical reaction involves only the separation, combination, or rearrangement of atoms - it does not result in the creation or destruction of atoms |
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Dalton`s atomic theory 4th hypothesis - Law of conservation of mass |
- matter can be neither created or destroyed - since mass is made of atoms that are unchanged in a chemical reaction- mass most also be conserved |
