Remember
Water can be a liquid or a solid or a
gas.
 Solids, liquids and gases have
different properties.
 Matter has three forms: solid, liquid
and gas.
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First Activity: What’s the Matter?
Write Yes or No in each box
Property
Assumes the
shape of its
container
Can be formed
into a sphere
Crumbles
Flows
Solid
Liquid
What’s the Matter? Activity
Cornstarch (1/4 cup)
 Water (1/8 cup)
 Craft stick
 Measuring cup
 Ziplocs
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Mix ingredients together in the
ziploc bag using the stick.Stir
quickly until the material is smooth.
Questions for What’s the Matter?
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Does the material look like a solid or liquid ?
Why?
Poke your finger into the material. Does it
behave like a solid or liquid? Why?
Take a spoonful of the material in your hand
and roll it into a ball. How did it behave?
Now place the ball on the desk. How did it
behave?
Pick it up again and hold it for a few minutes.
Do you observe any changes that
demonstrate the presence of a gas?
Is this material a solid, liquid or gas?
Key Concepts
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Solids have a fixed shape and volume
Liquids have a fixed volume but no
fixed shape.
Gases have neither a fixed volume or
shape.
In all 3 of these phases, the
matter is in the form of atoms,
molecules or ions.
 In solids, they are closely packed
and at relatively fixed positions.
 In liquids, they are closely packed,
but not in fixed positions.
 In gases, they are widely spaced
and not in fixed positions.
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Particle motion
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The states of matter (solid, liquid, gas)
depend on molecular motion.
In solids the atoms are closely locked
in position and can only vibrate.
In liquids, the atoms and molecules are
more loosely connected and can collide
with and move past one another.
In gases, the atoms and molecules are
free to move independently, colliding
frequently.
Particle Motion
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How do we know how much the atoms
or molecules move?
In solids, the vibration of the particles
in the lattice can be measured by
sending in beams of light of specific
energies
In liquids,the movement of the particles
is responsible for its ability to flow and
to dissolve other substances
In gases, the motion of the particles
and their collisions with the walls of the
container creates gas pressure
Phases of Matter (cont.)
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Are there really 3 phases of matter?
If so, then what phase is the matter in
the Sun? How about the stuff inside
fluorescent light bulbs? Or fire?
Most everything in the Universe that is
luminous is plasma -a fourth phase of
matter, in which the atoms are ionized,
or disassociated. Plasma is a common
subject in physics, but is not studied in
chemistry (or in the standards.)
Vocabulary
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Solid – phase of matter that has fixed
volume and shape
Liquid – phase of matter with fixed
volume but no fixed shape
Gas – phase of matter with neither
fixed volume nor shape
Note that all of these words have
different meanings in colloquial English
What are other meanings for the
word solid?
 Note that “gas” is often used as
slang for gasoline, which is a liquid,
and has nothing to do with the
usage of the word in this case.
 Why are some types of financial
accounts referred to as liquid?

Fill in the table below with
common items.
 Indicate whether the item is in the
form of solid, liquid or gas.
 Draw a picture of each item.
 Examples could include: water, ice,
steam. Others?
 Item
Phase
Drawing

Break: Something to think about
We are familiar with the effects that
an increase in temperature has on
melting solid ice to form liquid
water, or heating water to create
water vapor (steam)
 Are there other ways to change
phases? For example, can you melt
ice without changing the
temperature?
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Standard Connections
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Students know water can be a liquid or a
solid and can be made to change back and
forth from one form to the other (K)
Students know the properties of
substances can change when they are ..
cooled or heated (1)
Students know evaporation and melting are
changes that occur when objects are
heated (3)
How do we define temperature?
What are phase changes?
Defining temperature

A thermometer consists of a
chamber or bulb of liquid with a
long narrow tube attached.
When the liquid inside becomes
hotter, it expands and moves up
the tube. When it cools, it
contracts and moves back
down. The level of the liquid
can therefore be used as a
measure of the temperature of
an object.
Galileo’s
thermoscope
c. 1597
– Defining temperature
Given: beaker of water,
thermometer, hot plate
 Heat a beaker of water
with a thermometer in it.
 Record the temperature
every 30 seconds, until it
has been boiling at least
3 minutes.
 Graph the temperature
vs. time from your data.
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Questions for the Temperature
activity
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Where on your graph does the water
start to boil?
Does the temperature of the water
change in the same way before it has
begun to boil and after?
Explain how you can tell from your
graph.
How do we calibrate a thermometer?
Write an operational definition for
temperature.
Key concepts
On the Celsius scale, the boiling
point of water is defined as 100o C,
while the freezing point is defined
as 0o C.
 You can use these two fixed points
to define a temperature scale, and
to calibrate a thermometer.
 Water changes phase from liquid to
gas form when it boils.

Phase Changes
There is a complicated relationship
between temperature and pressure
that describes the phases of
matter for a substance.
 This relationship is summarised in
a phase diagram.
 For example, the boiling point of
water is 100o C at one atmosphere
pressure, but increases as the
pressure increases.

Phase Changes
Phase Changes
Phase Changes
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Boiling can occur at much lower
temperatures than 100o C – if the
pressure is also much lower than 1 atm.
Boiling therefore does not necessarily
mean hot – instead, it refers to the
process of changing liquid to gas
Along the boiling point line, water vapor
and liquid water can both exist
Heat is needed in order for the phase to
change from liquid to gas
Phase Changes
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The heat required to boil (1 g of) water
(without changing its temperature) is
called its heat of vaporization
Along the melting point line, ice and
liquid water can both exist
Heat is required in order to melt ice to
liquid water
The heat required to melt (1 g of) water
(without changing its temperature) is
called its latent heat of fusion
At the triple point, all 3 phases of water
can coexist
Lunch puzzler
 Consider a figure skater.
 How does the phase
diagram for water help you
to understand what
happens when the skater
presses her blades on the
ice?
 In other words, how does
ice skating work?
Standard Connections
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Students know metals have properties in
common, such as high…thermal
conductivity (5)
Students know heat flows in solids by
conduction (6)
How can we measure thermal conductivity?
What is the difference between
temperature and conductivity?
Third activity: Thermal
Conductivity
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Given: blocks of plastic, wood and
aluminum that have been sitting out in
the classroom for a while
Measure the temperature of each with a
thermometer. Do not hold them while
making the measurements – leave
them on the table
Place the inside of your wrist against
each object. How do they feel?
Third activity: Thermal
Conductivity
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According to your operational definition,
do the two blocks have the same
temperature?
Is it possible for two objects to feel
different to the touch and yet have the
same temperature?
Does the feeling of hotness or coldness
give a reliable indication of the
temperature of an object?
What is happening to make the objects
feel different?
Fourth activity: Math connections
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It takes one calorie of heat to raise the
temperature of 1 g of water by 1o C.
This is known as the specific heat of
water
The heat of vaporization (of 1 g) of
water (at 100o C) is 540 calories. (This
is how much it energy it takes to turn 1
g of water into 1 g of steam, without
changing its temperature.) Before and
after vaporization, the water and steam
remain at 100o C.
Fourth activity: Math connections
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The heat of fusion (of 1 g) of water (at
0o C) is 80 calories. (This is how much it
energy it takes to melt 1 g of ice into 1 g
of water, without changing temperature.)
Before and after melting, the water and
ice remain at 0o C.
How much heat does it take to melt 10 g
of ice, heat the resulting water up to
100o C, and then boil the water until 1 g
has turned into steam?
Fourth activity: Math connections
Standard Connections
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Students know water left in an open
container evaporates, but water in a
closed container does not (K)
Students know evaporation and melting
are changes that occur when objects are
heated (3)
Students know physical processes include
freezing and boiling in which a material
changes form with no chemical reaction
(8)
What is happening when water
evaporates?
Key concepts: Evaporation
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Evaporation occurs when some of the
molecules at the surface of the liquid
have enough energy to escape as gas
In a closed container, these molecules
stay trapped as vapor
Key concepts: Evaporation
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One way to estimate how much energy
is required to vaporize water at (for
example) 20oC room temperature is
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Vaporize 1 g of water at 100oC = 540 cal
Cool 1 g of steam from 100oC to 20oC = 40
cal (as you get 0.5 cal when you cool 1 g of
steam by 1 degree.)
So the total heat needed to evaporate 1
g of water at 20oC is about 580 cal. In
other words, 580 cal is removed from
the mass of liquid for every gram of
water that evaporates. This is why
evaporation is a cooling process.
Evaporation vs. Boiling
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Since the vapour particles are a gas, they can
exert pressure on the liquid or on the walls
and top of the container. This pressure is
called the vapour pressure.
When a liquid boils, the vapor pressure is so
large that bubbles form throughout the liquid,
and carry the gas particles to the surface,
where they boil off.
During evaporation, the vapour pressure is
less than the air pressure, so no bubbles are
formed. Vapour particles only leave from the
surface.
Evaporation vs. Boiling
Standard Connections
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Students know heat flows… in fluids by
conduction and convection (6)
Consider a pot water on an electric hot plate, which has
been boiling steadily for some time
Describe all of the heat transfers taking place at the
interfaces between the different elements: air, water,
pot, hot plate
What type of heat transfer is taking place at each
interface?
Heating and Cooling
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It is possible to keep foods quite cold
without a refrigerator by wrapping
them in a towel soaked in cold water.
Why does this procedure work?
In many places, it takes
weeks or months for snow
that accumulated during the
winter to melt. Why doesn’t
all of the snow melt as soon
as the temperature climbs
above 0oC?
Evaporation & Melting
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Students know evaporation and melting
are changes that occur when objects are
heated (3)
Is this third grade standard strictly true?
It requires energy to melt an object (heat
of fusion) BUT…
Evaporation can occur without heating an
object. In fact, it cools an object as it
removes the heat of vaporization.
Heating enhances the rate of
evaporation, but it is not necessary.
Calories and Calories
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We have defined a unit of heat (energy)
known as a calorie. For example, it takes 1
calorie to heat 1 g of water by 1 degree C.
The calories that are used in discussing the
energy content of food are usually written as
Calories (capital C). These Calories are equal
to1000 times the heat calorie (lower case c),
so they are also called kilocalories (kcal).
How much would a 200 Cal candy bar cause a
50 kg person’s temperature to rise (if they
could not cool off)? Assume the person is
made entirely of water.
Vocabulary
Boiling – process where heat is added to
turn a liquid into a gas
 Freezing – process where heat is
removed to turn a liquid into a solid
 Melting – process where heat is added
to turn a solid into a liquid
 Condensation – process where heat is
removed to turn a gas into a liquid

Vocabulary
Evaporation – surface process where
a liquid turns into a gas, removing heat
from the liquid
 Conduction – direct transfer of heat
from one object to another
 Convection – transfer of heat by the
formation of gas bubbles within a liquid
that is unevenly heated
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Academic Language
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Why do we say someone that is very angry
is boiling mad?
Why do we say someone who is motionless
is frozen in place?
Think of other common uses of the
vocabulary words that describe human
behavior, rather than physical phenomena
Analogies and Student
Involvement
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Ask the students to record their Caloric
intake for a day and make a list of what
they did during that day (school work,
activities, sports, etc.)
With the help of a reference book (Health
book for example), have them compare
their food calorie (C) intake, converted
into energy (c), with how much energy
they needed to do all the activities they
were involved in during that day.
Vaporization Challenge
Which will burn more? A gram of
boiling water at 100o C that hits
your skin (at a temperature of
around 40o C) or a gram of steam
at 100o C?
 Why?
 Explain your reasoning.

Sublimation
Materials like CO2 have phase
diagrams that show a different
relationship between pressure and
temperature compared to water
 At atmospheric pressure, CO2 is a
solid, which changes directly into a
gas
 This process is called sublimation

Phase Diagram for CO2
liquid
solid
gas
Questions about CO2
Compared to 1 atm and room
temperature, what type of
conditions are necessary for CO2 to
appear in liquid form?
 If the temperature is held
constant, what must happen in
order for CO2 to boil ?
 What must happen in order for
CO2 to freeze?
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Standard Connections
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Students know properties of solid, liquid
and gaseous substances, such as water
(H2O) .. and carbon dioxide (CO2). (5)
What differences did you observe
between water and carbon dioxide at
room temperature?
What phases will these substances be in
at a temperature of 100o C?