Chemistry Test Review
Your test will be:
• 10 short answer questions
• Each question is worth 10 points each
• Partial credit will be given
Hints for doing well on this test:
• Read each question carefully
• Answer the question you are asked
• Re-read each answer– Make sure you have answered the question
completely– Make sure your answer relates to the
question
Example Questions
And how to answer them
One of your friends stays overnight at your house. The next morning, your
mother cooks him some fried eggs for breakfast. He says, "I don't like fried eggs,
can you change them to poached eggs instead?"
– Use what you know about physical and chemical changes to explain why it
is NOT possible to change the fried eggs to poached eggs.
You MUST discuss changeschanges & whywhy in your answer
• It is not possible to change the fried eggs into poached eggs because cooking eggs is a chemical change
• Chemical changes produce new products that are very difficult to reverse
• Answer identifies cooking an egg as a chemical change
• Answer describes chemical changes as being difficult to reverse because the original substance is changed into a new substance
Scientists used to think electrons moved in orbits around the
nucleus. How do scientists currently describe the movementdescribe the movement of
electrons?
Notice the word movement – the question is not asking
about location only
• Electrons move in an electron cloud around the outside of the nucleus
• The electrons do not follow a particular path
Oxygen gas normally exists as O2 molecules. Each molecule contains
two oxygen atoms.
Is O2 a compound? Explain your answer.
Make sure you EXPLAINEXPLAIN
• No [answer]
• A compound must contain atoms from more than one element [explanation]
Why is the state of matter a physical property and
not a chemical property?
You must know the meaning of each of these
terms to answer this question
• State of matter
• Physical property
• Chemical property
Sometimes giving an example helps explain your
thinking:
• Changing state does not change the identity of the matter.
• Chemical properties can't be observed without changing the substance.
• Water is still water whether it is ice, liquid, or vapor. [example]
Vanadium, with an atomic number of 23, and bromine, with an atomic number of 35, are both in the same
period as germanium.
– Explain why bromine is most likely a non-metal.
– Explain why vanadium is most likely a metal.
• Vanadium is most likely a metal because it on the left side of the same period
• Bromine is most likely a non-metal because it is to on right side of the same period.
The operating system and programs that run on a
computer depend on tiny electrical circuit boards called
chips, which are made of materials called semi-
conductors. Based on the label "semi-conductor,"
which type of element would you predict is used to make computer
chips? Explain.
“Semi-Conductors”
• Metalloids because their ability to conduct electricity lies somewhere between the good metallic conductors and the poor nonmetallic conductors.
In the fall, you rake leaves into a pile, burn them, and spread the
ashes back on the lawn as fertilizer.
What are the chemical changes and what are the physical changes in this process?
Think about each part of the question
• Raking the leaves into a pile and spreading the ashes are physical changes.
• Burning the leaves and the ashes being broken down by the lawn for fertilizer are chemical changes.
Define the law of conservation of mass and explain how it
relates to physical and chemical changes.
2 Parts to this question
• Definition:– The law of
conservation of mass states that mass cannot be created or destroyed.
• Explanation:– This means that the
mass of any substances present before a physical or chemical change is equal to the mass of the substances present after the change.
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