Matter and Density Notes
Matter?
• Anything that takes up
space (volume) and has
mass (made up of
atoms) is called matter.
• So can you think of
anything that is matter?
• Even more difficult to do
can you think of anything
that is not considered
matter?
Atoms?
• The smallest basic unit of
matter is atoms.
• Atoms are the smallest
particles into which an
element can be divided and
still have the same
properties of that element.
• Atoms are made up of
smaller part known as
protons, neutrons, and
electrons.
Protons? Neutrons?
Electrons?
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Protons are a positively charged
portion of an atom which are
located in the nucleus of an atom.
Neutrons have no charge they are
also located in the nucleus of an
atom.
Electrons have a negative charge.
They are much smaller then
protons and neutrons and they
rotate randomly around the
outside of the nucleus.
Atoms (elements) vary in the
amount of protons, neutrons, and
electrons they have.
We are now discovering that
protons, electrons, and neutrons
are made up of even smaller parts
called quarks.
2 Problems with Atomic Models
• There are two problems with
the current atomic model.
• The electrons are much
smaller then the protons and
neutrons although they are
usually drawn similar in size.
Electrons are about 2000 times
smaller then protons and
neutrons.
• Atoms are actually mostly
empty space. There is a large
space (relative to the size of
the atom) between the nucleus
of the atom and the electrons.
Combining Atoms
• When you combine 2 or
more atoms together you
get a molecule.
• Atoms can combine
together by sharing
electrons.
• Examples of molecules are
things like H20 (water), C02
(carbon dioxide), C6H12O6
(glucose), C3H8 (propane),
C8H8O3 (mint), etc.
Development of the Atomic
Model
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The information we have about
atoms has changed a lot over the
past several hundred years.
Discovering different parts of an
atom such as the electron or
proton took a long time and
required lots of scientific tests.
Our ideas about atoms are likely
to change in the future even more
as we build upon past ideas and
develop new and better
technology.
As of right now we have never
seen an atom but we know
information about them because
of their effects.
You will be reading more about
these scientists soon.
Volume?
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The amount of space taken up, or
occupied, by an object is known
as the objects volume.
The volume of a liquid generally
measured in liters (L) or milliliters
(mL).
When measuring the volume of a
liquid you might notice the liquid
clings to the side of the graduated
cylinder or beaker you are using.
In science this is known as a
meniscus.
You always measure the volume
of a liquid from the bottom of its
meniscus.
The volume of a liquid is
measured with a graduated
cylinder.
Mass?
• Mass is the amount of matter
in an object.
• LOGICAL EXPLANATION
• So if mass is the amount of
matter in an object and matter
is something that has volume
and is made up of atoms.
Really mass is the amount of
atoms that make up an object.
• Mass is not the same as
weight.
• Mass is constant. No matter
where in the universe an
object is located its mass
remains the same.
Energy?
• The more the atoms or
molecules move in
substance the more
energy they have.
• This movement causes
them to have heat
energy.
• When you take the
temperature of something
you are really measuring
how quickly the
molecules in that
substance are moving.
Density?
• Density is a measure of how
compact the molecules or
atoms are in a substance.
• If molecules are more compact
we say they have a high
density. (Solids)
• If molecules are less compact
they have a low density. (gas)
• Snow can have different
densities that’s why sometimes
it is light and fluffy and easy to
shovel and other times it is
really weight and heavy.
4 States of Matter
• There are four states of
matter they are
• Solids: Table, Wall,
Chair, Desk, etc.
• Liquids: Water,
Mountain Dew, Coke
• Gases: Carbon Dioxide,
Methane, Propane,
Natural Gas
• Plasma: Lightning, Stars,
Comet Tails, Fireballs
made by Nuclear
Weapons
Phase of Matter-Solid
• Solids: Molecules are
packed very close
together in a definite
structure.
• These atoms/molecules
have low energy because
the molecules vibrate
slightly in place.
• These atoms/molecules
have a high density
because they are packed
tightly together.
Phase of Matter-Liquid
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Liquids: Molecules not as close
together, but still have an
attraction to each other.
Liquids have no definite structure
this means they will take the
shape of whatever container they
are put in.
Liquids have more energy in
solids because their
atoms/molecules move around
more. These molecules can
overlap and bump into one
another.
Liquids have a lower density then
solids but a higher density then
gases. Because of this liquids are
known to have intermediate
densities.
Phase of Matter-Gas
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Gas: Molecules spaced very far
apart from each other.
Gas molecules do not have a
definite structure. They will take
the structure or shape of their
surroundings.
Gas molecules have lots of
energy. They are constantly
moving around and bumping into
each other. (Diffusion)
Because gas particles have more
room in-between them they can
transfer energy as they collide
with one another. (Sound Energy)
Gas particles have a low density
because they are not packed very
close to one another.
Phase of Matter-Plasma
• Plasma: Molecules
have very high
energy. These
molecules are moving
around rapidly.
• Very rare state of
matter. Lightning,
stars, really hot fire,
etc. are made up of
plasma.
Phase Change
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A phase change is when you go
from one state of matter to
another.
Phase changes usually occur
because you are either adding
energy to a system and therefore
causing the molecules to speed
up or you are taking energy away
from a system and causing
molecules to slow down.
If I go from a solid to a liquid are
the molecules gaining energy or
losing energy?
Phase Changes-Melting
• Melting: Going from
a solid to a liquid.
• The molecules are
gaining more energy
as they speed up.
• Examples: Snowman
melting and an ice
cube melting in your
Mountain Dew
making it taste
watery.
Phase Change-Evaporation
• Evaporation: Material
goes from a liquid to a gas.
• Molecules speed up even
more. They are less
dense because there is
more space in between
them.
• Example: Puddle of water
forms after it rains but
eventually it evaporates
into moisture in the air.
Phases Changes-Sublimation
• Material goes directly
from a solid to a gas
and skips the liquid
phase.
• Sublimation occurs
when really cold
areas heat up quickly.
• Example: Dry Ice or
snow sublimating on
a mountain top.
Phase Changes-Condensation
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Condensation: Material goes
from a gas to a liquid.
The molecules are slowing down
and therefore losing energy.
Think about condensation on a
glass. Warm air particles in the
gas phase come in contact with a
cold substance. The cold
substance causes the air particles
to slow down or lose energy and
therefore condense into a liquid.
Examples: Condensation can be
left on your bedroom window
when it is nice and warm inside
but it is cold outside.
Phase Changes-Freezing
• Freezing: Going from a
liquid to a solid.
• The molecules are
losing energy and
becoming more dense.
• Examples: Putting ice in
the freezer. Frozen frost
on the ground when you
wake up in the morning.
Phase Changes-Deposition
• Going directly from a
gas to a solid this skips
the liquid phase.
• Molecules rapidly slow
down and increase in
density.
• Example: Water
particles in the air being
frozen directly onto a car
window forming a solid
sheet of ice.
Phase Change Diagram
Volume?
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The amount of space taken up, or
occupied, by an object is known
as the objects volume.
The volume of a liquid generally
measured in liters (L) or milliliters
(mL).
When measuring the volume of a
liquid you might notice the liquid
clings to the side of the graduated
cylinder or beaker you are using.
In science this is known as a
meniscus.
You always measure the volume
of a liquid from the bottom of its
meniscus.
The volume of a liquid is
measured with a graduated
cylinder.
More about Volume
• When scientists measure
the volume of a solid they
use centimeters cubed or
cm3.
• The word cubic means
having three dimensions.
• In science, cubic
centimeters or cubic
meters are the units used
most often for measuring
the volume of solids.
• The volume of a solid
measured with a ruler.
Volume Equation
• To find the volume of a
rectangular or square
there is a mathematical
equation.
• The equation is:
• Volume=Length x Width x
Height
• V=L x W x H
• Based on that equation
what would be the
volume of the box
pictured to the right.
Other ways to find out Volume
• A lot of times you
have a solid that are
irregularly shaped so
it would be impossible
to figure out a
constant height,
width, or length. (Ex:
Rock)
• How could you figure
out the volume of a
rock?
Other ways to find out Volume
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You can figure out the volume of
an irregularly shaped object by
placing it in water and seeing how
much water is displaced.
This means you take the
measurement of how much water
is in a graduated cylinder then you
place the object in the graduated
cylinder and see how much the
water level rises.
This will give you an answer for
volume in mL which you can
transfer to cm3 since you are
taking the volume of a solid.
Volume Practice Questions
• A book has a length
of 25 cm, a width of
18cm, and a height of
4cm. What is its
volume?
• A CD case is 14.2 cm
long, 12.4 cm wide,
and 1 cm deep. What
is its volume?
Mass?
• Mass is the amount of matter
in an object.
• LOGICAL EXPLANATION
• So if mass is the amount of
matter in an object and matter
is something that has volume
and is made up of atoms.
Really mass is the amount of
atoms that make up an object.
• Mass is not the same as
weight.
• Mass is constant. No matter
where in the universe an
object is located its mass
remains the same.
Mass vs. Weight
Mass and weight do not mean the same thing. Here are some
differences between them.
• Mass is the amount of
matter in an object.
• Mass is measured with a
triple beam balance.
• Mass is measured in
grams or kilograms.
• Mass is constant no
matter where in the
universe and object is
located its mass remains
the same.
• Weight is the gravitational
force exerted on an object.
• Weight is measured with a
spring scale.
• Weight is measured in
Newtons (N). One Newton is
equal to the weight of an object
that has a mass of 100 grams
on earth.
• Weight is not constant in
changes depending upon your
location.
• Your Weight on other Planets.
Mass vs. Weight
• Mass and weight are
different but they are
related.
• For example an object with
more mass, has a greater
gravitational force exerted
on the object.
• A building would feel the
effects of gravity a lot more
then a person. That’s one
reason why we can jump
and fight off gravity
momentarily and a building
can’t.
Density?
• Density is a measure of how
compact the molecules or
atoms are in a substance.
• If molecules are more compact
we say they have a high
density. (Solids)
• If molecules are less compact
they have a low density. (gas)
• Snow can have different
densities that’s why sometimes
it is light and fluffy and easy to
shovel and other times it is
really weight and heavy.
How to calculate density?
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Density can be calculated using
the following equation.
Density=Mass/Volume
So density really is determined by
two factors mass and volume.
If the mass of an object goes up
the density of an object goes up.
If the mass of an object goes
down the density of an object
goes down.
However the opposite is true for
volume. If the volume of an object
goes up the density of the object
goes down. If the volume of an
object goes down then the density
of the object goes up. This is an
inverse (or opposite) relationship.
Microwave Soap Demo
Density Problems
• I have a small race
car that has a mass of
15 grams and a
volume of 3.5 cm3.
• What is the density of
the race car?
• D=M/V
• D=15g/3.5cm3
• D=4.28 g/cm3
Density Problems
• I have fish tank that has a
height of 75cm, a width of
34cm, and a length of 112cm.
• I also know the mass of the
fish tank is 945 grams.
• What is the density of the fish
tank?
• V=LxWxH
• V=75cmx34cmx112cm
• V=285,600cm3
• D=M/V
• D=945g/285,600cm3
• D=.0033 g/cm3
Density Problems
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I have an igneous rock that is
225 grams and when I place the
rock in a graduated cylinder the
level of the water goes from
44mL to 77mL.
What is the density of my rock?
V=Amount of water afterAmount of water before
V=77mL-44mL
V=33mL
Since it is a rock the volume is
not in mL it is in cm3. So the
volume is 33cm3.
D=M/V
D=225g/33cm3
D=6.818 g/cm3
Density of Water
• Water has a density of 1
g/ml.
• If an object floats in water
then I know that object has
a higher density then
water. (higher then 1 g/ml)
• If an object sinks in water
then I know that object has
a lower density then water.
(lower then 1/gml)
• Density Spheres
Demonstration
Density Problems?
• I have a rock that has a
mass of 45 grams and a
volume of 97cm3.
• Will it float or sink in
water?
• D=M/V
• D=45g/97cm3
• D=.46 g/cm3
• The object will float in
water because it is less
dense then water.
Density Problems?
• Rivers naturally sort
rocks and sediments as
they push them down
stream.
• What would happen to
the most dense
sediments? (boulders
or big rocks)
• What would happen to
the least dense
sediments? (sand or
dirt)
Density Problems?
• If I blow up a balloon
with air have I
increased or
decreased the
balloons density?
• The balloons density
decreased. Why?
• If the volume
increases remember
the density
decreases.
Density Problems?
• The earth has 4 layers.
They are the crust, mantle,
outer core, and inner core.
• Which layer do you think is
the most dense?
• Inner Core. Why?
• When the earth first formed
it was a mixture of various
materials. The most dense
materials sunk towards the
middle of the earth.