Models of the Atom

Rutherford realized that the atomic nucleus was positively charged because

• it attracted alpha particles.

• it deflected alpha particles.

• it had no effect on alpha particles.

• it produced alpha particles.

Niels Bohr added _______________ to the model of the atom.

• electrons.

• a nucleus.

• neutrons.

• energy levels.

Alpha particles have a charge of +2 and a mass of four atomic mass units (amu). Because the mass was greater than the charge, James Chadwick concluded that atoms contain

• a nucleus.

• positive material in which electrons are embedded.

• neutrons.

• negative particles that cancel part of the positive charge.

J.J. Thomson discovered electrons, and he also knew that atoms are neutral. From these two facts, Thomson inferred that the atom also contains

• positive material.

• a nucleus.

• neutrons.

• energy levels.

If an atom were enlarged so that the nucleus were the size of a marble, then the entire atom would occupy the volume of a(n)

• tennis ball.

• basketball.

• large beach ball.

• football field.

A line emission spectrum is produced when electrons

• become excited and move from ground state to higher levels in an atom.

• leave the atom completely.

• fall from higher, excited states back to lower or ground state.

• move from a cathode to an anode.

Which of the following are incorrectly paired?

• Cathode Ray Tube/ Electron discovery

• Gold Foil Experiment / Proton discovery

• Alpha particle mass/charge / Neutron discovery

• Emission Spectrum / Energy Level discovery

In 1897, J J Thomson discovered the electron. This led him to propose the (a)   -pudding model of the atom.

What was the expected result of the alpha scattering experiment if the plum pudding model was correct?

• Most of the alpha particles would pass straight through the foil.

• Most of the alpha particles would be completely reflected.

• The alpha particles would be absorbed by the gold foil.

• The gold foil would produce extra alpha particles.

Most of the alpha particles passed straight through the gold foil. This led Rutherford to propose that...

• most of the atom was empty space.

• there was a positively charged nucleus at the centre of the atom.

• the alpha particles were not aimed properly at the foil.

• the plum pudding model was correct.