Notesale: Turn your study into money

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The Atom, development of the current model
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This is also where the word atom comes from as the ancient Greek word “atomos” means
indivisible
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Nothing really happened in the development of the idea until the English chemist John Dalton,
1766-1844, worked out that an element consist of only one type of atom and when there is a
reaction to create a compound which will consist of more than one type of atom
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Dalton's
model of an atom was a solid small object
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J
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By experimentation he learn that these small particles
were negatively charged and about 2000 times smaller than the lightest element, hydrogen
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Because atoms are neutrally
charged, Thomson came up with a model of that atom which had the negatively charged electrons in
an atom surrounded by a cloud of positive charge
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This was the accepted model until Ernest Rutherford proved otherwise
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They expected the alpha particles to punch through the matter of
the gold foil and overcome the repulsion of the positive charge spread throughout the atom
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Rutherford came up with a new model of the atom to explain this, as most alpha
particles were unaffected the positive charge in the atom must be concentrated in a very small
volume
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Rutherford came up with a model of a nucleus of positive charge surrounded by lots of
empty space with the electrons orbiting in this space
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This theory was proposed to explain why when heated atoms give off light
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Sources
http://www
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co
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shtml
http://www
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com/chemistry/demo/units/LR301
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C
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Snow

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