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 carbon dioxide: CO2 (solid form is dry ice)
7th Grade Physical Science SLEs
(Student Learning Expectations)
1 atom of carbon + 2 atoms of oxygen
= 1 molecule of carbon dioxide
PS.5.7.1
Explain how a small number of naturallyoccurring elements can result in the large
variety of substances found in the world.
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O – C – O = CO2
Depending on the source of information,
there are between 88-92 naturally
occurring elements on Earth. These
elements may combine to form
o elemental molecules such as O2
and H2
o compounds such as H2O and CO2
o mixtures such as in the air (O2, Ar,
and CO2 dissolved in N2)
Substances found in the world include
elements, compounds, and mixtures.
2 or more elements combine chemically to
form compounds.
Ex.: C + O + O = CO2 (carbon dioxide),
H + H + O = H2O (water),
Na + Cl = NaCl (sodium chloride – table salt),
Fe + Fe+ O + O + O = Fe2O3 (iron oxide),
N + H + H + H = NH3 (ammonia)
2 or more substances (elements,
compounds, and mixtures) are physically
combined to form mixtures.
There are a huge number of possible
combinations of elements in forming these
compounds and mixtures.
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
1 atom of sodium + 1 atom of chlorine
= 1 molecule of sodium chloride
Na – Cl = NaCl
Sodium Chloride (salt crystal)
……………………………………………………
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PS.5.7.2
Create models of common compounds:

sodium chloride (table salt): NaCl
iron II oxide: FeO or iron III oxide: Fe2O3
1 atom of iron + 1 atom of oxygen
= iron II oxide
water : H2O
Fe – O = FeO
2 atoms of hydrogen + 1 atom of oxygen
= 1 molecule of water
2 atoms of iron + 3 atoms of oxygen
= iron III oxide
H – O – H = H2O
O – Fe – O – Fe – O = Fe2O3
Hematite: mineral form of iron oxide
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ammonia: NH3
The compound water is a clear,
tasteless liquid that is safe to drink. The 2
elements that chemically combine to form
water are:
1 atom of nitrogen + 3 atoms of hydrogen
= 1 molecule of ammonia
H
= NH3
H–N–H
o hydrogen: a colorless, odorless gas.
Extremely flammable and explosive.
Inhaling high concentrations of
hydrogen gas will cause breathing to
stop.
o oxygen: a colorless, odorless gas.
Oxygen gas is not flammable itself, but
it does support combustion.
…………………………………………..………
PS.5.7.3
Identify compounds as substances consisting of
two or more elements chemically combined.

Compounds are:
 made of 2 or more different elements
 the elements are chemically combined
 a chemical reaction is required to
separate the elements back out of the
compound
carbon dioxide (CO2): is composed of the
elements carbon and oxygen.
The compound carbon dioxide is a
colorless and odorless gas at room
temperature. Inhaling large amounts may
cause breathing to stop. The 2 elements
that chemically combine to form carbon
dioxide are:
o carbon: a black, odorless solid that is
combustible (will burn).
PS.5.7.4
Compare and contrast properties of
compounds to those of the elements that
compose them:

Water (H2O): is composed of the
elements hydrogen and oxygen.
o oxygen: a colorless, odorless gas.
Oxygen gas is not flammable itself, but
it does support combustion.
salt (NaCl) : sodium chloride is
composed of the elements sodium and
chlorine.
PS.5.7.5
Demonstrate techniques for forming and
separating mixtures:
The compound sodium chloride is
common table salt. It is in the form of
white cubic crystals that are safe to eat in
small amounts. The 2 elements that
chemically combine to form table salt are:
Forming mixtures: mixing 2 or more substances
together. Ex.: mixing chocolate in milk to form
chocolate milk, stirring salt into water to form salt
water, mixing soil in water to make muddy water
o sodium (Na): a soft, silvery metal that
explodes in water. It will burn skin,
eyes, or internal tissues.
o chlorine (Cl): a greenish-yellow gas
which is toxic when excessive amounts
are inhaled or ingested.
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Separating mixtures: mechanically or physically
separating the parts in a mixture.
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chromatography: used to separate the
colors in a mixture of colors. Ex.:
separating the colors that are contained in
black ink
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settling: used to separate the substances in
a suspension according to their different
densities. Ex: allowing the suspended soil
to settle out of a mixture of soil and water.
The soil will settle to the bottom because it
is denser than the water.
magnetic attraction: used to separate a
magnetic substance (iron, nickel, cobalt) from
a nonmagnetic substance. Ex.: separating
iron filings from a mixture of sulfur and
iron filings.
evaporation: used to separate a dissolved
solute from a solution. Ex.: separating the
salt from a solution of salt water
soil
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water
PS.5.7.6
Classify substances as
 elements:
o Elements are pure substances that
make up all matter. They cannot be
separated by chemical or physical
means.
o Elements are organized in the periodic
table of the elements.
o Each element has its own symbol such
as H for hydrogen.
o
Some elements and their symbols
include;
carbon C
sodium Na
hydrogen H
argon Ar
oxygen O
helium He
iron Fe
copper Cu
nitrogen N
filtration: used to separate a solid (or
suspension) from a liquid. Ex.: separating
sand from a mixture of sand and water
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
carbon dioxide CO2
water H2O
glucose C6H12O6
ammonia NH3

Solution
salt water
Kool-aid
Solute(s) dissolved in
salt
flavor powder and
sugar
air
oxygen, argon, and
carbon dioxide
sterling silver copper
compounds:
o Compounds are made of 2 or more
different kinds of elements that are
chemically combined.
o Each molecule of a compound is
exactly like every other molecule of
that compound.
o Each compound is represented by its
own chemical formula.
o Some compounds and their formulas
include;
iron oxide Fe2O3 or FeO
table salt NaCl
isopropyl alcohol C3H8O
Colloids:
milk, fog, cloud
silly putty
marshmallows
shaving cream
pudding
nitrogen
silver
PS.5.7.8
Investigate the effect of variables on solubility
rates
 size of the particles (surface area):
breaking a solute into smaller pieces,
increases the surface area on which the
solvent can work to dissolve. (grind up
sugar cubes to make smaller particles)
 stirring: stirring liquids and solids (such
as salt into water) increases the rate of
solubility (the salt dissolves faster when
stirred)
 temperature: for solids and liquids, more
solute dissolves when the temperature
increases. The opposite happens with
gases.
 amount of solute already dissolved:
Solutes dissolve faster when only a little
solute is already dissolved. As the solution
becomes more concentrated, the rate of
solubility decreases.
Mixtures:
o Mixtures are made of 2 or more
substances that are physically
combined.
o Mixtures may vary in the amount of
each substance that is present.
o Some mixtures of different types and
examples include;
Solutions:
salt water
Kool-aid
hairspray
dry air
sterling silver
Solvent
water
water
Suspensions:
muddy water
sand in water
lake water
PS.5.7.9
Interpret solubility graphs
PS.5.7.7
Distinguish among solvent, solute, and solution
 A solution is a homogenous mixture (the
solute is evenly mixed throughout the
solvent.)
 The solute is the substance(s) that
dissolves in the solvent. The solute is the
substance that is in the smaller amount.
There may be more than one solute in a
solution.
 The solvent is the substance in which the
solutes dissolve. It is the substance that is
in the largest amount.
Graph A:
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Use the solubility graph A on the previous page
to answer :
1. Which solute’s solubility is most affected
by temperature change of the solvent?
_________________________________
2. Which solute’s solubility is least affected
by temperature change of the solvent?
_________________________________
3. What can you say about the solubility of
potassium nitrate as the temperature of the
water increases?
__________________________________
4. What is the solubility of sodium nitrate in
water at 60oC? ______ g/100mL
PS.7.7.3
Conduct investigations to identify types of
potential energy and kinetic energy
potential energy – stored energy
kinetic energy – energy of motion
Graph B:
Look at the diagram on the preceding page:
Think about the pipe insulation roller coaster lab;
Gravitational potential energy was highest at the
highest point on the roller coaster. Kinetic energy
is highest at the bottom where the marble is
rolling the fastest.
Use the solubility graph B to answer :
1. Which solute’s solubility is most affected
by temperature change of the solvent?
___________________________________
2. Which solute’s solubility is least affected
by temperature change of the solvent?
___________________________________
3. What can you say about the solubility of
NaCl as the temperature of the water
increases? __________________________
___________________________________
4. What is the solubility of KBr in water at
130oC? ______ g/100mL
5. Which solute has the greatest solubility in
water at 60oC? ______________________
At 90oC? ___________________________
The rubber-band stores elastic potential energy.
Hot molecules have more kinetic energy than
cool molecules. Notice in the illustration how
energy of motion is shown.
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PS.7.7.2
Describe alternatives to the use of fossil fuels:
solar energy, geothermal energy, wind,
hydroelectric power, nuclear energy, biomass
Energy is the ability to do work.
Biomass is renewable energy from plants and
animals.
Hydropower plant changing the energy from
moving water to electrical energy.
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Solar energy is energy from the sun.
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Geothermal energy is generated deep inside the
Earth.
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Radiant energy from the sun has powered life
on Earth for many millions of years.
Solar energy can be used for heat & to
generate electricity
Photovoltaic (PV devices) or “solar cells”
change sunlight directly into electricity.
This photograph shows a vertical geothermal well
test in the Nevada Desert.
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Hydropower is energy from moving water.
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Beaver Dam
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PS.6.7.1-6.7.5Compare and contrast Newton’s three
laws
of
motion;
Conduct
investigations
demonstrating Newton’s first law of motion;
Demonstrate Newton’s second law of motion;
Conduct investigations of Newton’s third law of
motion; Explain how Newton’s three laws of
motion apply to real world situations (e.g., sports,
transportation)
Wind energy is energy from moving air.
Newton’s 1st Law of Motion:
An object at rest stays at rest and an object in
motion stays in motion with the same speed and in
the same direction unless acted upon by an
unbalanced force.
Also sometimes called the law of inertia.
Inertia is a property of matter. Matter wants to
remain as it is (either resting or moving)
How Uneven Heating of Water and Land
Causes Wind
Examples:
Wind farm made up of wind turbines (windmills)
used to generate electricity
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Nuclear Energy is energy from atoms. It is
energy in the nucleus (core) of an atom and is a
nonrenewable energy resource.
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Tablecloth is removed (pulled by an unbalanced
force) while dishes stay on the table. The dishes
were at rest and an unbalanced force did not act
on the dishes.
The sun is basically a giant ball of hydrogen
gas undergoing fusion (atoms nuclei fuse
together) into helium gas and giving off vast
amounts of energy in the process.
Nuclear power at nuclear power plants comes
from fission (splitting of the atom’s nucleus).
Bicycle stops but the rider continues in motion
over the handlebars. The bicycle was acted upon
by an unbalanced force (uneven ground) but the
rider was not acted on by that unbalanced force
(until of course he lands).
Nuclear Power Plant
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Newton’s 3rd Law of Motion:
For every action there is an equal and opposite
reaction. (action-reaction)
Newton’s 2nd Law of Motion:
Force = Mass X Acceleration
(F=MA)
"Forces always occur in pairs. If object A exerts a
force F on object B, then object B exerts an equal and
opposite force –F on object A"
The change in velocity caused by a force depends
on the mass and speed of the object.

Acceleration is in the direction of the
force.
Pushing force to the right
Pulling force to right
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object moves right
object moves right
If you push or pull with twice the force,
the object accelerates to twice as fast.
If an object is being acted on by a force of 2 N and
then more force is added for a total of 4 N, the object
will move twice as fast as it did at 2 N. (If a wagon is
pulled with twice the force, the wagon will accelerate
until it is traveling twice as fast.)
This is a picture demonstrating Newton's third law. It
has an action force pushing the skateboard forward
and a reaction force pushing back with the same force
in the opposite direction.

As mass increases, acceleration slows.
(If more children are added to the wagon and the force
does not change, the wagon will slow down.
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