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VideoIn 422 BC, Democritus reasoned that matter must be made of small particles that were indivisble and therefore named them atomos (Greek word for indivisible)
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Was a french chemist who calculated measurements of chemical change in a sealed container. He observed that the mass of the reactant in the container before a chemical reaction was equal to the mass of the products after.Video
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VideoAnother french chemist observed that the composition of water is always 11% hydrogen and 89% oxygen by mass. Decovered the Law of Definite Proportions-the elements that compose a compound are always in a certain proportion by mass.
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Dalton is the father of atomic theory.
Discovered:
1. Matter is composed of tiny, indivisible particles known as atoms. - Proven wrong because atoms contain protons, neutrons, and electrons.
2. Atoms of the same element are identical, and atoms of any one element are different from those of another. - Proven wrong becuase of isotopes.
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- Reactions occure when atoms are separated from one another, joined, or rearranged, but matter cannot be created or destroyed. This is the Law of Concervation of Mass.
- Atoms of different elements can combine in whole number ratios form compounds - Law of Definite Proportions and Law of Multiple Proportions.
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videoDiscovered electrons and protons using a cathode ray tube.
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videoUsed the Gold Foil Experiment to make the "Plum Pudding" Model of the atom- the positive mass was dotted with negatively charged electrons.
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VideoUsed the Oil Drop Experiment to find the negative charge of an electron.
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VideoProved the existance of the neutron.
