Unit 3: Understanding the Atom

Which part of the atom makes up most of its volume?

• its electron cloud

• its neutrons

• its nucleus

• its protons

What did Democritus believe an atom was?

• a solid, indivisible object

• a tiny particle with a nucleus

• a nucleus surrounded by an electron cloud

• a tiny nucleus with electrons surrounding it

If an ion contains 10 electrons, 12 protons, and 13 neutrons, what is the ion's charge?

• 2-

• 1-

• 2+

• 3+

J. J Thomson's experimental setup is shown. What is happening to the cathode rays?

• They are attracted to the negative plate.

• They are attracted to the positive plate.

• They are stopped by the plates.

• They are unaffected by either plate.

Tags

NGSS.HS-PS2-5

NGSS.HS-PS3-5

How many neutrons does iron-59 have?

• 30

• 33

• 56

• 59

Why were Rutherford's students surprised by the results of the gold foil experiment?

• They didn't expect the alpha particles to bounce back from the foil.

• They didn't expect the alpha particles to continue in a straight path.

• They expected only a few alpha particles to bounce back from the foil.

• The expected the alpha particles to be deflected by electrons.

Which determines the identity of an element?

• its mass number

• the charge of the atom

• the number of neutrons

• the number of protons

What does the figure show?

• two different elements

• two different ions

• two different isotopes

• two different protons

How is Bohr's atomic model different from Rutherford's model?

• Bohr's model has a nucleus.

• Bohr's model has electrons.

• Electrons in Bohr's model are located farther from the nucleus.

• Electrons in Bohr's model are located in circular levels.

Which best describes an atom?

• a particle with a single negative charge

• a particle with a single positive charge

• the smallest particle that still represents a compound

• the smallest particle that still represents an element