Atoms and their structure

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16 to 8 is a 2 to 1 ratio.

True because you have to add a whole atom, you can’t add a piece of an atom.

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Parts of Atoms

J. J. Thomson - English physicist. 1897

Made a piece of equipment called a cathode ray tube.

It is a vacuum tube - all the air has been pumped out.

A limited amount of other gases are put in

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Thomson’s Experiment

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Metal Disks

Slide 13

Passing an electric current makes a beam appear to move from the negative to the positive end

Thomson’s Experiment

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Thomson’s Experiment

By adding an electric field

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Thomson’s Experiment

By adding an electric field he found that the moving pieces were negative

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By adding an electric field

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Thomson’s Experiment

Used many different metals and gases

Beam was always the same

By the amount it bent he could find the ratio of charge to mass

Was the same with every material

Same type of piece in every kind of atom

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Thomsom’s Model

Found the electron.

Couldn’t find positive (for a while).

Said the atom was like plum pudding.

A bunch of positive stuff, with the electrons able to be removed.

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Millikan’s Experiment

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Millikan’s Experiment

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Millikan’s Experiment

X-rays

X-rays give some drops a charge by knocking off electrons

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Millikan’s Experiment

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Millikan’s Experiment

They put an electric charge on the plates

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Millikan’s Experiment

Some drops would hover

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Millikan’s Experiment