Question

chapter 4 atomic structure
thomsons model of the atom (pages 102 - 103)

1. use the words in the box below to fill in the blanks. objects with like electric charges _, and objects with opposite electric charges _.

attract reflect, deflect repel

1. thomson concluded that the particles in the glowing beam had a(n) _ charge because they were attracted to a positive plate.
2. circle the letter of the sentences that describe thomsons model of the atom.

a. an atom is filled with positive matter.
b. an atom is mostly space with a small nucleus.
c. negative charges are scattered throughout an atom.
rutherfords atomic theory (pages 104 - 105)

1. an _ is a fast - moving particle that carries a positive charge.
2. circle the letters of the sentences that describe what happened when marsden directed a beam of particles at a piece of gold foil.

a. more alpha particles were deflected than expected.
b. none of the alpha particles were deflected.
c. some alpha particles bounced back toward the source.

1. circle the letter of the sentence that states what rutherford concluded from the gold foil experiment.

a. an atoms negative charge is concentrated in its nucleus.
b. an atoms positive charge is concentrated in its nucleus.
c. an atoms positive charge is spread evenly throughout the atom.

Explanation:

1. Objects with like electric charges repel, and objects with opposite electric charges attract, based on basic electro - static principles.
2. Particles attracted to a positive plate must have a negative charge as opposite charges attract.
3. Thomson's model had positive matter with negative charges scattered throughout. So a and c describe it.
4. An alpha particle is a fast - moving particle with a positive charge.
5. In the gold foil experiment, more alpha particles were deflected than expected and some bounced back, so a and c are correct.
6. Rutherford concluded that an atom's positive charge is concentrated in its nucleus.

Answer:

1. repel; attract
2. negative
3. a. An atom is filled with positive matter.; c. Negative charges are scattered throughout an atom.
4. alpha particle
5. a. More alpha particles were deflected than expected.; c. Some alpha particles bounced back toward the source.
6. An atom's positive charge is concentrated in its nucleus.