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 changes &
why in your answer
• It is not possible to
• Answer identifies
change the fried eggs
cooking an egg as a
into poached eggs
chemical change
because cooking
• Answer describes
eggs is a chemical
chemical changes as
change
being difficult to
• Chemical changes
reverse because the
produce new products
original substance is
that are very difficult
changed into a new
to reverse
substance
Scientists used to think
electrons moved in orbits
around the nucleus.
How do scientists currently
describe 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 EXPLAIN
• 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.