Notes

1.Which statements belong to Dalton’s atomic theory? Select all that apply.

Atoms have a massive, positively charged center.
Atoms cannot be created or destroyed. X
Atoms cannot be broken down into smaller pieces. X
All atoms of an element are identical.
Chemical reactions cause atoms to be rearranged. X
Electrons are located in energy levels outside of the nucleus.

2.The first model of the atom was developed through

scientific experimentation and data analysis with water vapor and gases.
observation of the light emitted by elements when they are heated.
thinking about the smallest particles of matter without experimenting. Y
analyzing the effects of a magnet on the path of a cathode ray.

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

His results gave people a picture of what atoms look like for the first time.
His results gave the first clues that atoms could be created and destroyed.
His results gave the first experimental evidence that matter is made up of atoms. X
His results gave the first evidence that atoms were made up of smaller particles.

4.
What did Bohr’s model of the atom include that Rutherford’s model did not have?

a nucleus
energy levels
electron clouds X
smaller particles
5.
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 pick up an electric current. The electrodes are named “positive” and “negative,” which were words used by Benjamin Franklin in the 1700s to describe electricity. A bright ray forms in the gas when an electric current is applied to metal electrodes. In the 1800s, an important scientist suspected that the negatively charged particles in a cathode ray were present in all atoms.

What procedure would allow that scientist to investigate this idea?

observing if the cathode ray forms when the electric current is off
making cathode ray tubes out of different materials to see if the ray is the same
using different magnets to see if the cathode ray responds in the same way to each X
changing the strength of the electric current and observe how the ray forms and changes
6.
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?

An atom’s negative particles are surrounded by positive matter, so the positive particles are easier to remove.
An atom’s positive particles are surrounded by negative matter, so the negative particles are easier to remove.
An atom’s smaller negative particles are at a distance from the central positive particles, so the negative particles are easier to remove. Y
An atom’s larger positive particles are at a distance from the central negative particles, so the positive particles are easier to remove.
7.The plum pudding model of the atom states that

each atom has an overall negative charge.
each atom has a dense, positively charged center.
an atom is a solid, indivisible sphere that makes up all matter. X
an atom is made up of electrons in a sea of positive charges.
8.
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?

Electrons do not follow specific paths, so describing the area where an electron is likely to be is more scientifically accurate.
Electrons were thought to be negatively charged, but now scientists know that their charge depends on their energy level. X
The modern model is based on mathematical equations, so the results become less clear when the decimals are rounded.
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.
9.
What new characteristic did John Dalton add to the model of the atom?

An atom is a round, solid mass. X
An atom has a massive, positive center.
An atom is made up of smaller particles.
An atom can join with other kinds of atoms.
10.What did Rutherford’s model of the atom include that Thomson’s model did not have?

a nucleus
energy levels
electron clouds X
smaller particles