Transcript Unit 1 - 8th Grade Physical Science

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Classify each of the following as a solid,
liquid or gas: apple juice, bread, a textbook
and steam.
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The physical forms in which a substance can
exist: solid, liquid, gas or plasma
What are particles of matter??
◦ Matter is made up of tiny particles called atoms.
They are so small that we cannot even see them.
◦ These particles, atoms, are constantly in motion
and bumping into each other. How atoms interact
with each other helps us to classify which state of
matter a substance is in.
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Solids have a definite shape and volume
The particles in a solid are very close together
and cannot move much. They can only
vibrate in place.
There are 2 types of solids:
◦ Crystalline: particles are in a very orderly 3-D
arrangement. They have repeating patterns in
rows. Ex: iron and diamond
◦ Amorphous: particles have no special arrangement.
Ex: glass, rubber and wax
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A liquids shape changes to fit the container
but it has a definite volume.
The particles are not packed as tightly as they
are in a solid. They can move around and
slide past each other allowing the liquid to
take the shape of the container.
Surface Tension: the force at the surface of a
liquid that sometimes causes it to fall in
drops.
Viscosity: a liquids resistance to flow
◦ Maple syrup has a high viscosity
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Gases have no definite shape or volume
The particles in a gas move quickly and can
even break away from each other.
There is much less attraction between the
particles in a solid. The space between the
particles is constantly changing to fill up all
available space.
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A hot ionized (charged) gas
◦ Because the particles are so energetic the negative
and positive parts of the atom begin to separate
causing charged areas in this super heated gas
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Strongly influenced by electric and magnetic
fields.
Found in stars, the sun, lightning and neon
signs
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As an ice cube melts it changes from a solid
to a liquid. Discuss the similarities and
differences between the solid ice and liquid
water.
 The solid has a fixed shape and volume, the liquid will
still have the same volume but will be able to take the
shape of its container.
 The atoms in the liquid will be moving a little bit more
than those of the solid because the have gained more
energy through the transfer of heat.
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When a substance changes from one form to
another.
****In order for a substance to change state, we must
ADD or REMOVE energy. In most cases, energy
takes the form of heat.
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This occurs when you ADD energy or
INCREASE the temperature.
As the temperature increases the particles
move faster.
At a certain point, called the MELTING POINT,
the solid melts.
Melting is ENDOTHERMIC because energy is
gained in the form of heat by the substance.
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This is the reverse of melting.
We must REMOVE heat or LOWER temperature
for this to happen.
Freezing is EXOTHERMIC because you are
removing energy from the substance.
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Occurs when a liquid reaches its BOILING
POINT.
This process occurs at the surface of a liquid
that has reached it boiling point.
Is this process endothermic or exothermic?
◦ Endothermic – energy is added
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**Boiling point and melting point are the
same regardless of the amount of
substance**
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This is the opposite of evaporation.
The CONDENSATION POINT is the point when
gas turns to liquid.
Is the process endothermic or exothermic?
◦ Exothermic – energy is removed
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The attraction between particles must be
completely overcome so that they go from
tightly packed to far apart.
Endothermic or Exothermic?
◦ Endothermic – energy is added
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When a substance gains or loses energy it
must either change temperature or change
state.
As the temperature changes the particles
change their speed equally.
HOWEVER: The temperature of a substance
does not actually change until the change of
state is complete.
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How can you easily loosen the metal lid of a
glass jam jar? Why does this work?
You hang up an air freshener in your car and
you can smell it throughout the whole car.
Why is this?
Energizer
Using your phase change handout from yesterday,
place the following labels in the correct areas:
freezing/melting point, boiling/evaporation point,
all ice, ice and water, all water, water and steam, all
steam
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Elements:
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Compounds:
◦ Definition?
◦ Definition?
◦ What do the particles
look like?
◦ What do the particles
look like?
◦ What makes an
element unique?
◦ What must occur for
a compound to be
broken down?
◦ What is the definition
of a pure substance?
◦ What are some
examples of
breakdown methods?
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Study the diagram, what is happening to state
and temperature at point Z if you are moving
to the left?
Z
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What is the difference between evaporation,
vaporization and boiling?
◦ Vaporization refers to a liquid turning into a gas
◦ Evaporation occurs at the surface of a liquid and
does not require the entire mass to reach the
substances boiling point
◦ Boiling occurs when you heat up a liquid to a
certain point, forcing it to begin to vaporize