Three States of Matter
Three States of Matter
You’ve just walked home on one of the coldest days of the year. A fire is
blazing in the fire place. And there is a pot of water on the stove to
make hot chocolate. The water begins to bubble. Steam rises from the
pot. You make your hot chocolate, but it is too hot to drink. You don’t
want to wait for it to cool down. So, you add an ice cube. You watch the
ice melt in the hot liquid until the drink is at just the right temperature.
Then, you enjoy your hot drink while warming yourself by the fire.
The scene described above has examples of the three most familiar
states of matter: solid , liquid , and gas . The states of m atter are the
physical
forms
in
which
a
substance can exist. For example,
water commonly exists in three
states of matter: solid (ice), liquid
(water), and gas (steam).
Solids Have Definite Shape
and Volume
You can notice that marble in a bottle, keeps its original shape and
volum e. The marble’s shape and volume stay the same no matter what
size bottle you drop it into because the marble is a solid. A solid is the
state of matter that has a definite shape and volume.
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The particles of a
substance in a solid
state are very close
together. The
attraction between
them is stronger
than the attraction
between the
particles of the same
substance in the
liquid or gaseous state.
The particles in a solid move, but they do not m ove fast enough to
overcome the attraction between them. Each particle vibrates in place.
Therefore, each particle is locked in place by the particles around it.
Liquids Change Shape but Not Volume
The only thing that would change when the juice is poured into the
glass is the shape of the juice. The shape changes because juice is a
liquid. Liquid is the state of matter that has a definite volum e but
takes the shape of its container . The particles in liquids move fast
enough to overcome some of the attractions between them. The
particles slide past each other until the liquid takes the shape of its
container. Although liquids change shape, they do not easily change
volume. A can of juice contains a certain volume of liquid. That volume
stays the same if you pour the juice into a large container or a small
one.
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Liquids Have Unique Characteristics
A special property of liquids is surface tension . Surface tension is a
force that acts on the particles at the surface of a liquid. Surface tension
causes some liquids to form spherical drops, like the beads of water.
Gases
Would you believe that one small tank of helium can fill almost 700
balloons? How is this possible? After all, the volume of a tank is equal to
the volume of only about five filled balloons. The answer has to do with
helium’s state of matter.
Gases Change in Both Shape and Volume
Helium is a gas. Gas is the state of matter that has
no definite shape or volume. The particles of a gas
m ove quickly . So, they can break away completely
from one another. There is less attraction between particles of a gas
than between particles of the same substance in the solid or liquid state.
The amount of em pty space between gas particles can change. Look
at the balloon in the figure and how it can be com pressed . The
particles of helium in the balloons are
farther apart than the particles of helium in
the tank. The particles spread out as
helium fills the balloon. So, the amount of
empty space between the gas particles
increases.
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Worksheet
Question one: Choose the best answer:
1. One property that all particles of matter have in common is
they
a. never move in solids.
b. only move in gases.
c. m ove constantly.
Understanding
d. None of the above
Key Ideas
2. The change from a solid directly to a gas is called
a. evaporation.
b. boiling.
c. melting.
d. sublimation.
3. Which of the following statements best describes the
particles of a liquid?
a. The particles are far apart and moving fast.
b. The particles are close together but m oving past each other.
c. The particles are far apart and moving slowly.
d. The particles are closely packed and vibrating in place.
4. Which of the following statements describes what happens
as the temperature of a gas in a balloon increases?
a. The speed of the particles decreases.
b. The volum e of the gas increases, and the speed of the particles
increases.
c. The volume of the gas decreases.
d. The pressure of the gas decreases.
5. Boiling points and freezing points are examples of
a. chemical properties.
b. physical properties.
c. energy.
d. matter.
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6. What happens to the volume of a gas inside a cylinder if the
temperature does not change but the pressure is reduced?
a. The volum e of the gas increases.
b. The volume of the gas stays the same.
c. The volume of the gas decreases.
d. There is not enough information to determine the answer.
7. The atoms and molecules in matter
a. are attracted to one another.
b. are constantly moving.
c. move faster at higher temperatures.
d. All of the above
Critical
thinking
Question two: Answer the following:
1. Describe solids, liquids, and gases in terms of shape and volume.
 The particles of a substance in a solid state are very close
together. Each particle vibrates in place.
 The particles in liquids m ove fast enough to overcom e
som e of the attractions betw een them . The particles slide
past each other until the liquid takes the shape of its
container.
 The particles of a gas m ove quickly. So, they can break
aw ay com pletely from one another.
2. Use the following terms in one sentence: evaporation and solids .
Evaporation takes place w hen liquids changes to gas but
sublim ation takes place w hen solids changes directly to gas .
3. Classify each substance according to its state of matter: apple juice,
bread, a textbook, and steam..
 Apple juice is a liquid.
 Bread and a text book are solids.
 Steam is a gas.
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4. The volume of a gas can change, but the volume of a solid cannot.
Explain why this is true.
Because particles of a gas m ove quickly and they can break aw ay
com pletely from one another filling all the container but the
particles in a solid are very close together. Each particle
vibrates in place.
Question three: Answer the following:
Rosie poured some lavender
oil into an oil burner.
She heated it with a candle.
The oil changed state.
Which diagram represents this change of state? Write the letter.
____________ B ____________________ .
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Resources:
 Holt science and Technology - Physical science.
ISBN-13: 978-0-030-46228-3
Unit two – Section one- page 66.
 SAT Science Exam KS3 , 2007.
 SAT Science Exam KS3 , 2008.
 Websites:
http://www.google.com.qa/imgres?q=diagram+solid+liquid+gases&hl=en&qscrl
=1&nord=1&rlz=1T4RNRN_enUS444US445&biw=1280&bih=513&tbm=isch&tbn
id=EnWNrRdokhAboM:&imgrefurl=http://martine.people.cofc.edu/111LectWeek
1.htm&docid=rloHX7VRY5RwM&imgurl=http://martine.people.cofc.edu/111LectWeek1_files/image008.jpg&
w=305&h=228&ei=8CjUT6CKNYfWrQf_zu37Dw&zoom=1&iact=hc&vpx=308&vp
y=160&dur=4843&hovh=182&hovw=244&tx=167&ty=139&sig=109337572700
176211273&page=1&tbnh=147&tbnw=196&start=0&ndsp=11&ved=1t:429,r:1,s
:0,i:70
http://www.google.com.qa/imgres?q=gas+particles&hl=en&sa=X&qscrl=1&nor
d=1&rlz=1T4RNRN_enUS444US445&biw=1280&bih=513&tbm=isch&prmd=imv
ns&tbnid=52yiLR4cDuA1M:&imgrefurl=http://www.mit.edu/~kardar/teaching/projects/chemo
taxis(AndreaSchmidt)/more_random.htm&docid=oooKWZPkM6QJkM&imgurl=htt
p://www.mit.edu/~kardar/teaching/projects/chemotaxis(AndreaSchmidt)/gas_
particles.gif&w=212&h=200&ei=xEbUT7uiIYizrAe08PH7Dw&zoom=1&iact=hc&v
px=1004&vpy=197&dur=1469&hovh=160&hovw=169&tx=93&ty=73&sig=1093
37572700176211273&page=1&tbnh=122&tbnw=129&start=0&ndsp=14&ved=1
t:429,r:6,s:0,i:153
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