Atomic Theory I: Cathode Rays, Electrons and the Nucleus

Prior to experiments with cathode tubes, the smallest particles that made up matter were believed to be _____.

• a.atoms
• b.corpuscles
• c.electrons
• d.particles of rarefied air

The nuclear model of the atom held that

• a.electrons were randomly spread through "a sphere of uniform positive electrification."
• b.matter was made of tiny electrically charged particles that were smaller than the atom.
• c.matter was made of tiny, indivisible particles.
• d.the atom had a dense, positively charged nucleus.

Which scientist’s experiments resulted in the nuclear model of the atom?

• a.Ernest Rutherford’s gold foil experiments.
• b.Johann Hittorf’s experiments with objects in vacuum tubes.
• c.Robert Millikan’s oil drop experiments.
• d.William Crookes’ experiments passing a current through vacuum tubes.

J.J. Thomson proved that cathode rays were beams of _____.

• a.alpha particles
• b.atoms
• c.electrons
• d.oil droplets

In Millikan’s oil drop experiment, what was the consequence of making the electrical force (q E) equal to the gravitational force (m g)?

• a.The oil drops were suspended, motionless in the chamber.
• b.The oil drops fell downward due to the force of gravity.
• c.The oil drops fell downward due to the electrical force.
• d.The oil drops were propelled upward by the electrical force.

Which sequence shows the correct order of discovery, with the earliest first?

• a.Cathode rays, nuclear model, Plum Pudding model, quantum model
• b.Cathode rays, Plum Pudding model, nuclear model, quantum model
• c.Cathode rays, Plum Pudding model, quantum model, nuclear model
• d.Plum Pudding model, cathode rays, nuclear model, quantum model

In Rutherford’s gold foil experiment, some of the alpha particles passed straight through the gold foil, completely undeflected. What could Rutherford conclude from this observation?

• a.Alpha particles have a positive charge.
• b.Electrons have a positive charge.
• c.The atom is made up of mostly empty space.
• d.There must be a small, positively charged dense area within the atom.

What is the value of the charge on an electron?

• a.Negative 1.60 x 10^-19 corpuscles
• b.Negative 1.60 x 10^-19 coulombs
• c.Positive 1.60 x 10^-19 corpuscles
• d.Positive 1.60 x 10^-19 coulombs

Electrons, interacting with gaseous atoms in partially evacuated tubes, created Faraday’s "dark space."

• a.true
• b.false

Which scientist discovered the electron?

• a.Michael Faraday
• b.William Crookes
• c.J.J. Thomson
• d.Ernest Rutherford