AnswersReed Fall 2026 Physical Science 2nd Semester 7th HourAtomic Theory

Atomic Theory Answers

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1
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Why did Thomson’s results from experimenting with cathode rays cause a big change in scientific thought about atoms?

A
His results gave people a picture of what atoms look like for the first time.
B
His results gave the first clues that atoms could be created and destroyed.
C
His results gave the first experimental evidence that matter is made up of atoms.
D
His results gave the first evidence that atoms were made up of smaller particles.
2
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The charged particles in the beams that Thomson studied came from atoms. As these particles moved away from their original atoms, they formed a visible beam. The current model of the atom includes protons, neutrons, and electrons.What is the best use of an atomic model to explain the charge of the particles in Thomson’s beams?

A
An atom’s negative particles are surrounded by positive matter, so the positive particles are easier to remove.
B
An atom’s positive particles are surrounded by negative matter, so the negative particles are easier to remove.
C
An atom’s smaller negative particles are at a distance from the central positive particles, so the negative particles are easier to remove.
D
An atom’s larger positive particles are at a distance from the central negative particles, so the positive particles are easier to remove.
3

Which scientist developed the first model of the atom that proposed the structure of the inside of an atom?

A
Dalton
B
Bohr
C
Rutherford
D
Thomson
4

The modern model of the atom describes electrons in a little less specific detail than earlier models did. Why is it that being less sure about the placement of electrons in an atom is actually an improvement over earlier models?

A
Electrons do not follow specific paths, so describing the area where an electron is likely to be is more scientifically accurate.
B
Electrons were thought to be negatively charged, but now scientists know that their charge depends on their energy level.
C
The modern model is based on mathematical equations, so the results become less clear when the decimals are rounded.
D
The position of electrons in atomic models has changed so much that it is better to have a less specific model than to be wrong again.
5

Scientists have changed the model of the atom as they have gathered new evidence. One of the atomic models is shown below.

Question illustration
A
A few of the positive particles aimed at a gold foil seemed to bounce back.
B
The colors of light emitted from heated atoms had very specific energies.
C
Experiments with water vapor showed that elements combine in specific proportions.
D
Cathode rays were bent in the same way whenever a magnet was brought near them.
6

A cathode ray tube is made of glass with a small amount of some kind of gas in it. It has metal electrodes at each end to pick up an electric current. The electrodes are named "positive” and "negative."What are one of the main uses of this device ?

A
to speed up the flow of current flowing through a wire
B
to examine a beam of charged particles
C
to magnetize different atoms within a space
D
to change the strength of a proton within an atom
7

Scientists have changed the model of the atom as they have gathered new evidence. One of the atomic models is shown below.What experimental evidence led scientists to change from the previous model to this one?

Question illustration
A
A few of the positive particles aimed at a gold foil seemed to bounce back.
B
The colors of light emitted from heated atoms had very specific energies.
C
Experiments with water vapor showed that elements combine in specific proportions.
D
Cathode rays were bent in the same way whenever a magnet was brought near them.
8

Which statement describes one feature of Rutherford’s model of the atom?

A
The atom is mostly empty space.
B
The atom cannot be divided into smaller particles.
C
Electron clouds are regions where electrons are likely to be found.
D
The electrons are located within the positive material of the nucleus.
9

What new characteristic did John Dalton add to the model of the atom?

A
An atom is a round, solid mass.
B
An atom has a massive, positive center.
C
An atom is made up of smaller particles.
D
An atom can join with other kinds of atoms.
10

What did Bohr’s model of the atom include that Rutherford’s model did not have?

A
a nucleus
B
energy levels
C
electron clouds
D
smaller particles

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