Review for Matter and Energy Unit Test
You will be quizzed on the following learning targets. Be sure you can clearly answer each learning
target.
LT1 - All matter is composed of atoms and atoms combine chemically to form molecules.
a. Define and give examples of atoms and molecules.
b. Distinguish between oxygen air and oxygen atoms.
c. Give examples of atoms and molecules that are in our atmosphere.
d. Represent atoms and molecules using drawings, chemical formulas, and ball-and-stick models.
LT2 - Matter is conserved in chemical changes, while atoms are rearranged or
In chemical changes, atoms are rearranged, while mass is conserved.
a. Explain how mass is conserved when substances undergo a chemical change.
b. Describe what happens to atoms and molecules during chemical changes.
c. Explain how burning ethanol is an example of chemical change, using evidence from the lab
and the definition of chemical change. Explain what we see on a macroscopic scale and what we know is
happening on an atomic-molecular scale.
d. Honors: Write chemical changes as balanced equations. (Ex. C2H5OH + 3O₂ → 3H₂O + 2CO₂)
e. Honors: When given the reactants of a chemical change, predict the products.
LT3 – Energy is conserved and transformed in chemical changes.
a. Define chemical potential energy (aka chemical energy).
b. Give examples of high-energy bonds.
c. Identify forms of energy that are present when ethanol is burned (before and after).
d. Describe how energy is conserved when ethanol is burned, using evidence from the Burning
Ethanol Lab and molecule models.
LT4 – Organic and Inorganic molecules differ in their bonded atoms.
a. Identify and draw examples of organic and inorganic molecules with the appropriate bonds.
b. Identify organic and inorganic materials by their origin.
During this unit, we are considering chemical changes, which occur at the atomic-molecular scale. In
biology, we study chemical changes that happen within living systems. When molecules undergo a
chemical change, it means that the molecules are broken down and the atoms re-combine to form
different molecules. In simple chemical changes, this could look like a single molecule forming two or
more molecules, or two or more molecules combining to form a single molecule. Although the
reactants (starting molecules) are different from the products (ending molecules), the number of
each type of atom remains the same. In other words, matter is conserved in chemical changes.
In the Burning Ethanol Lab, we observed what happened to ethanol when we burned it in a closed
system. When we lit ethanol on fire, it started a chemical change that can be represented by the
following chemical equation:
C2H5OH + 3O2  3H2O + 2CO2
Again, this equation shows that matter was conserved because the number of carbon, hydrogen, and
oxygen atoms are the same on both sides of the equation. In the lab, we saw evidence that carbon
dioxide was being produced because the BTB changed color, from blue (no CO2 present in the system)
to yellow (CO2 present in the system). We also saw evidence that water vapor was being produced,
because the cobalt chloride strip turned pink/white and steam collected on the sides of the
container.
The burning ethanol lab also showed us how chemical potential energy is transformed into heat and
light energy. Chemical potential energy is contained within high-energy bonds, C-C and C-H bonds.
When those bonds are broken during a chemical change, the energy contained within those bonds is
released as heat and light energy.
Organic materials are materials which originate from living things. Foods, fuels, and bodies of living
things are all considered organic. In biology, the difference between inorganic and organic material
lies in their molecular structure. Organic materials contain high-energy bonds, C-C and C-H bonds.
Inorganic materials do not have high-energy bonds. One way to distinguish between organic and
inorganic materials is to test whether or not they are combustible.
Question
Rules to Follow
Evidence to Look For
The Movement Question:
Where are atoms moving?
Where are atoms moving
from?
Where are atoms going to?
Atoms last forever in combustion
and living systems
All materials (solids, liquids, and
gases) are made of atoms
When materials change mass,
atoms are moving
When materials move, atoms
are moving
The Carbon Question: What
is happening to carbon
atoms?
What molecules are carbon
atoms in before the
process?
How are the atoms
rearranged into new
molecules?
Carbon atoms are bound to other
atoms in molecules
Atoms can be rearranged to
make new molecules
The air has carbon atoms in CO2
Organic materials are made of
molecules with carbon atoms
• Foods
• Fuels
• Living and dead plants
and animals
The Energy Question: What
is happening to chemical
energy?
What forms of energy are
involved?
How is energy changing
from one form to another?
Energy lasts forever in
combustion and living systems
C-C and C-H bonds have more
stored chemical energy than C-O
and H-O bonds
We can observe indicators of
different forms of energy
• Organic materials with
chemical energy
• Light
• Heat energy
• Motion
Additional practice questions can be found on the class website:
www.sciencewithmswang.weebly.com