Practice Unit 7

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1) Which label points to the part of the atom that has a neutral charge?

• A
• B
• C
• D

2) Atoms are the building blocks of all matter. Which of the following are the building blocks of atoms?

• elements
• molecules
• pure substances
• subatomic particles

3) By whom was this model of an atom proposed?

• Thomson
• Dalton
• Rutherford
• Bohr

4) Based on what you know about changes in matter, which statement explains why the diagram shows a purely physical change rather than a chemical change with changes in physical properties?

• The particles get smaller.
• The volume of the matter decreases.
• The composition of the matter stays the same.
• The particles change into particles of different substances.

5) Which process is an example of a chemical change?

• an iron nail rusting
• bath water cooling while you take a bath
• a piece of metal being heated until it expands
• a glass window breaking when hit with a baseball

6) When paper is burned, the mass of the remaining ash is less than the mass of the original paper. Which statement best explains this result?

• The ash has less volume than the paper.
• Some of the matter is destroyed during the reaction.
• The mass of the ash cannot be accurately determined.
• Some of the products of the reaction were given off as a gas.

7) The periodic table of the elements is divided by a line that zigzags along the right side. Which of the following is true for most of the elements that lie along the zigzag line?

• They are metals.
• They are metalloids.
• They are nonmetals.
• They are transition metals.

8) Which of the following explains why elements in Group 18 do not readily form compounds?

• These elements are very reactive.
• These elements are very unreactive.
• These elements are within the same period.
• These elements have the same atomic number.