3.2 Defining the Atom

What was the primary outcome of JJ Thomson's work regarding the atom?

• He discovered the proton

• He discovered the neutron

• He discovered the electron

• He discovered the nucleus

What is the primary purpose of Rutherford's Gold Foil Experiment?

• To discover new elements

• To test the strength of gold

• To understand the distribution of mass in an atom

• To prove the existence of electrons

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What are alpha particles used in the Gold Foil Experiment?

• Neutrally charged particles

• Positively charged particles

• Negatively charged particles

• Uncharged particles

Why did Rutherford choose gold foil for his experiment?

• It is magnetic

• It is the heaviest metal

• It can be made extremely thin

• It is the least reactive metal

According to Rutherford's hypothesis, what happens when alpha particles hit the dense positive center of an atom?

• They pass through without deflection

• They are absorbed by the nucleus

• They deflect at large angles

• They are scattered randomly

What did Rutherford observe about most of the alpha particles in his experiment?

• They were absorbed by the foil

• They reflected back to the source

• They passed straight through the foil

• They changed into beta particles

How did the Gold Foil Experiment support the idea that an atom is mostly empty space?

• Most alpha particles passed through without deflection

• All alpha particles were deflected

• Alpha particles created a new element

• Electrons filled the entire atom

In the Plum Pudding Model, what was expected to happen to alpha particles?

• They would pass through without interaction

• They would cluster around the electrons

• They would be deflected by a diffuse positive charge

• They would be absorbed by the protons

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What was one significant observation made during the Gold Foil Experiment?

• All particles were deflected equally

• Some alpha particles were deflected at large angles

• Alpha particles were absorbed by the foil

• Electrons were emitted from the foil

Why was the model of the atom changed after Rutherford’s experiment?

• The nucleus was discovered to be negatively charged

• The atom was shown to be solid throughout

• The nucleus was discovered to be a dense positive center

• Electrons were found to be in the nucleus