Describe the plum pudding model of the atom.

In the plum pudding model, negative electrons are evenly dispersed within a ball of positive charge.

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Describe the atomic model proposed by Dalton.

Atoms are solid spheres that cannot be broken down into smaller parts.

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What are the differences between the nuclear and plum pudding models of the atom?

Differences between the nuclear model and the plum pudding model include:

1The nuclear model has a nucleus, plum pudding model doesn't. 

2The positive charge in the nuclear model is compact, in the plum pudding model it is spread out.

2The mass in the nuclear model is compact, in the plum pudding model it is spread out.

4The electrons are around the outside in the nuclear model, in the plum pudding model they are evenly dispersed.

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Explain why some alpha particles were repelled by the gold foil.

Alpha particles are positively-charged so they were repelled by the positive nuclei of the gold atoms.

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What conclusion can be made from the observation that most alpha particles passed through the gold foil in a straight line?

Most of the atom is empty space.

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Describe Rutherford's experiment which provided evidence for the existence of a nucleus.

Rutherford fired alpha particles at a thin sheet of gold foil inside a vacuum. 

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Explain how the results of Rutherford's experiment disproved the plum pudding model.

The paths of some alpha particles were deflected at large angles by the atoms of gold.

This could only happen if the positive charge was concentrated (not spread out as the plum pudding model suggested).

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Describe how Neils Bohr improved Rutherford's nuclear model of the atom.

Bohr showed that electrons around the outside orbit the nucleus in fixed shells or energy levels.

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Which subatomic particle did James Chadwick discover?

James Chadwick discovered the neutron.

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Describe one flaw of the nuclear model of the atom.

It could not explain why the atom did not collapse in on itself. 

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