matter lesson 4: motion of particles

Unit 2: States of Matter

Lesson 4: Motion of Particles

Develop a model that shows the relationship between particle motion and states of matter.

Then, learn about the effect of pressure and temperature on particle motion and predict state changes as a result of pressure and temperature changes.

How do atoms and molecules move in solids, liquids, and gases?

Observations

A – Ice Cold Water

B – Room Temperature Water

C – Hot Water

Watch as teacher performs this demonstration.

•Label three beakers as A, B, and C.

•Fill Beaker A with 200 mL of ice water.

•Fill Beaker B with 200 mL of room temperature

water.

•Fill Beaker C with 200 mL of hot water.

•Start the timer.

•In each beaker, add two drops of blue and two

drops of yellow food coloring at the same time

(do not stir the samples).

•Measure the amount of time that passes

before the entire sample, including the ice, has

turned green.

•Answer the questions in your notebook.

OBSERVING PHENOMENA

OBSERVING PHENOMENA

1. How would you describe the motion of the blue and yellow dyes once they were added to the beaker?They moved randomly until they filled the entire beaker.2. How might you explain why the dye molecules did not go straight to the bottom of the beaker or move in straight lines?The dye molecules are particles that bounce around. They change direction each time they hit another particle.3. Which sample of water required the least time to completely turn green?hot water changed color the fastest.4. What might the green color signify?When the molecules of food coloring are evenly distributed throughout the entire molecule.5. How was the macroscopic behavior of the dye in Beaker A different from Beaker B and Beaker C?The dye moved more slowly in Beaker A than the other two. It took longer for it to mix and turn green.

OBSERVING PHENOMENA

Phenomenon: Drops of food coloring dissolve into water at very different rates depending on the temperature of the water.

What questions do you have about this phenomenon?list them in your notebook

A cold lump that looks like ordinary ice sinks to the bottom of a clear

liquid. Bubbles of smoky vapor gurgle to the top, as if the mixture is boiling. Yet,

the liquid is about the same temperature as the room. Something must be

different! As the bubbles burst to the surface, the vapor pours down the sides of

the beaker. You can tell that this is no ordinary gas because it sinks in the

surrounding air and clings to the tabletop like a heavy fog. What is going on

here?

The solid material is actually “dry ice.” Dry ice looks like the ice that you might

get from your freezer, but it acts nothing like it. It sinks in water instead of

floating at the water's surface. It also seems to boil instead of melt when placed

in cool water. That's because dry ice is not frozen water. It is frozen carbon

dioxide. Water and carbon dioxide are different substances, so they can take

different forms at the same temperature. At room temperature, carbon dioxide is

a gas. When the dry ice warmed up, the carbon dioxide formed bubbles of gas

that floated up.

In previous lessons, you learned that different substances have different

properties. In this lesson, you will learn what causes the same substance to

have different properties under different conditions. You will learn how the

behavior of particles explains their macroscopic appearance. Additionally, you

will learn how the temperature and pressure of a substance determine the

substance's properties. Recognizing the relationship between temperature and

pressure and a substance's state of matter allow you to predict how a

substance will behave in different situations.

Introduction p55

1. Molecular Motion in Solids p56

A state of matter is the physical form matter takes on as determined by the arrangement and motion of its atoms or molecules.The three most common states of matter on Earth are solid, liquid, and gas.

1. Molecular Motion in Solids p56

Solid• atoms or molecules are closely/tightly packed and touching one another• Particles are unable to move around – Fixed in place• Vibrate in place• a macroscopic amount of solid is considered to have a fixed shape and

volume

2. Molecular Motion in Liquids p57

Liquid• atoms or molecules are closely packed and touching one another but are not held in fixed

positions.• The atoms or molecules of a liquid vibrate and can also move around each other.• liquids are able to flow.• The shape of a macroscopic amount of liquid can change to take on the shape of its

container as its molecules flow around each other.• the molecules of liquids are able to slip past one another they fill in any gaps around them.• Gravity pulls them downward, and they slide past one another until they have filled up any

free space and taken the shape of the lower part of their container.

3. Molecular Motion in Gases p58

Gases• atoms or molecules are separate from each other by empty space and can move independently.• a gas's shape is even more changeable than a liquid’s.• the particles of gases are always moving.• Particles are spread apart• They do not even touch, except when they run into one another.• The molecules of a gas move this way in random directions until they happen to fill the entire

container.• a macroscopic amount of gas takes the shape and volume of its container.• the shape and volume of a gas depends on the shape and volume of its container.

1. Draw the particle motion of a solid. 3. Draw the particle motion of a liquid. 5. Draw the particle motion of a gas.

2. How does the particle motion

of a solid affect its macroscopic

behavior?

Because the particles are

tightly packed, a solid

does not appear to

change shape or size

from a macroscopic perspective.

4. How does the particle motion of a

liquid affect its macroscopic behavior?

The particles flow around each other, so

a liquid will flow and slosh on a

macroscopic level. The substance takes

the shape of the container it is in

because gravity pulls the particles

downwards until they have filled up the

free space at the bottom of a container.

6. How does the particle motion of a

gas affect its macroscopic behavior?

The particles move independently

of each other. However, since they

are not tightly packed together,

they move in random directions

until they fill the entire container,

they are in. As a result, a

macroscopic amount of gas takes

up the entire space of the container

it is in and can change shape

depending on its container.

4. Temperature Affects the State of Matter p59

The temperature of a substance helps determine its state.The melting point of a substance is the temperature at which it changes from a solid to a liquid as thermal energy is added to it.The boiling point of a substance is the temperature at which it changes from a liquid to a gas as thermal energy is added to it.All substances have a specific Melting Point and Boiling PointMelting point and Boiling point are properties that can be used to identify a substance.

Solid: below 0°C

32°F

Liquid: between

0°C - 100°C

32°F – 212°F

Gas: above

100°C

212 °F

4. Temperature Affects the State of Matter Review

1. Draw the particle motion of these substances at the following temperatures.

2. Using what you know of particle motion in solids,

liquids, and gases, explain why you think temperature

changes affect a substance's state of matter.

Use the terms particle motion, temperature, solid,

liquid, and gas in your answer.

As the temperature increases, a substance changes

from solid to liquid to gas.

Therefore, as the temperature increases, the

particles that make up a substance must move and

spread out more.

A solid particles will move faster and spread out to

become a liquid.

In a liquid, the particles flow around each other, but

are still touching. The liquid particles will spread out

even farther and move faster to become a gas.

In a gas, the particles move independently and do

not touch unless they bump into each other.

The opposite may be true when you remove energy.

Use this space to take notes

L4 Investigation 1 Modeling states of

MatterYou will tape the

handout as a “flip-up” for the Phet simulation

INVESTIGATION 1

MODELING STATES OF MATTER

You probably use the term temperature to describe the weather or even your food.

Although terms like warm, cold, and hot are great for everyday language, the scientific meaning of

temperature has more to do with particles, their motions, and the energy involved in those motions.

To start, come up with your own model of the three states of matter.

INVESTIGATION 1


How does the arrangement of particles in each state differ from the others?Solid: particles touching – fixed positionliquid: loosely held particles; still touchingGas: particles are spread out How does the motion of particles in each state differ from the others?Solid: closely packed, vibrating particles;Liquid: flowing particles; Gas: independently moving particles

Act-it-Out: SolidsIf each member of your group was a water molecule in a piece of ice, would you arrange yourselves in a rigid pattern, a loose pattern, or no pattern at all?Water molecules in ice are arranged in a rigid, regular pattern.Pretend that each member of your group is a water molecule in a solid piece of ice.Arrange the desks to form an appropriate container for you and your group members.Model the arrangement and behavior of water molecules in ice.How should the water molecules be arranged to best represent a solid?atoms or molecules are closely packed and touching one another.How should each of you move, relative to one another?The molecules should vibrate in place.

Act-It-Out: LiquidsIf each member of your group was a water molecule in a glass of liquid water, would you arrange yourselves in a rigid pattern, a loose pattern, or no pattern at all?Molecules in a liquid are arranged in a loose, flowing pattern.Pretend that each member of your group is a water molecule in a glass of liquid water.Arrange the desks to form an appropriate container for you and your group members.Model the arrangement and behavior of water molecules in liquid water.How should the water molecules be arranged to best represent a liquid?Molecules are closely packed and touching one another but are not held in fixed positions, so they move around.How should each of you move, relative to one another?The molecules should move past one another with loose, flowing motions.

Act-it-Out: GasesIf each member of your group was a water molecule in a cloud of steam, would you arrange yourselves in a rigid pattern, a loose pattern, or no pattern at all?Molecules in a gas are arranged in no pattern at all.Pretend that each member of your group is a water molecule in a cloud of water vapor.Arrange the desks to form an appropriate container for you and your group members.How should the water molecules be arranged to best represent a gas?Molecules arranged in no pattern with plenty of space between them.How should each of you move, relative to one another?You should move freely around.When the container is open, what might happen to the water molecules?They can escape from the container.

INVESTIGATION 1


Scientists use the Celsius scale to compare the temperature of objects. There are other temperature scales, but the Celsius scale is the one most commonly used in the study of matter.Why do you think it is important for scientists to use the same temperature scale?

INVESTIGATION 1


The state that matter takes depends in part on its temperature. At what temperatures does water change states?below 0°C is a solid; between 0°C and 100°C is a liquid; above 100°C is a gas.What are the temperatures at which a substance changes state from solid to liquid and liquid to gas called?The temperature at which a substance changes from solid to liquid is called the melting point. The process of changing from a liquid to a gas is called boiling, and the temperature at which this occurs is called the boiling point of a substance.

Which state requires the highest temperature to reach?

Gas

Phet simulationGet tablet……..

Using the States simulation, observe the molecular motion of a solid, liquid, and gas.

INVESTIGATION 1


Wrap UpHow does the temperature of a substance determine its state?As the temperature of a substance increases, the particles of the substance move faster. This results in state changes from solid to liquid to gas.How does the microscopic behavior of molecules affect the macroscopic behavior of a substance?The particle motion determines the state of matter, and each state behaves differently. Particles in a solid vibrate in place, so solid substances are rigid. Liquid particles move more loosely, so they can take the shape of their containers. Gas particles move about freely, so gases fill their containers.In the group activity, you used your bodies to model the three states of matter. How else could you model states of matter?Make a drawing of each state of matter or use spheres to represent particles and move them the ways that they move in each state of matter.

5. Pressure Affects State of Matter p60

Pressure is the amount of force exerted over a certain area.Pressure and ParticlesWhen a gas particle collides with an object, such as the walls of a container, it exerts a force on that object.• When many particles of matter bump

against the walls of a container, they exert a total force over the entire area of the container.

• That pressure depends on the force each individual particle exerts during a collision and the number of particles.


Scientists often describe the pressure exerted by a gas with the unit kilopascals.

One kilopascal (kPa) is equal to 1,000 newtons per square meter.

The pressure exerted by air on the surface of objects is about 101 kPa.


Air pressure is greater at sea level than at the top of a mountain because the air particles are more densely spaced at sea level.

They are spread farther apart at higher elevations.

Where air is denser and its particles are more tightly packed, there are more particles colliding over a certain area and thus a greater pressure.


The pressure of the surrounding air is different at different elevations.

If you fill an empty bottle of air at a high elevation, the air in the bottle is less dense and exerts low pressure on the bottle.

When you bring it down to sea level, the air particles outside are more densely packed, and the pressure is higher than at higher elevations.

As a result, the bottle crumbles to match the higher density.


How Pressure Affects State of Matter

Like temperature, there is a cause-and-effect relationship between changing the pressure exerted on a sample of a substance and the state of matter of a substance.


At a constant temperature of 100°C and a pressure of 50 kPa, the water inside is a gas.All of its particles are free to move about the container independently of one another.If you squeezed down on the piston, and the molecules of water inside would be squeezed into a smaller space.The pressure would increase.At a higher pressure of 200 kPa, all of the water vapor would be compressed, or squeezed, into the liquid state.


Pressure also affects boiling and melting points.A change in pressure changes the temperature at which a substance will change from a liquid to a gas.A decrease in pressure will decrease the boiling temperature.So, for water, as you increase in elevation and thus decrease in air pressure, the boiling temperature will decrease.In fact, many cooking websites give different instructions for cooking at high elevations where the boiling point of water is well below 100°C.For this reason, a more accurate description of a substance's boiling point includes the pressure at which it boils. Likewise, the melting point of a substance is affected by the pressure.

5. Pressure Affects State of Matter Review

1. Use arrows to indicate the pressure the gas particles exert on the inside and outside of the containers.

5. Pressure Affects State of Matter Review

3. Using what you know of particle motion in solids, liquids, and gases, explain why you think pressure changes affect a substance's state of matter. Use the terms particle motion, pressure, solid, liquid, and gas in your answer.________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

As the pressure increases, a substance can

change from gas to liquid to a solid.

This is because the particles are compressed at

higher pressures.

This results in the particles having less space to

move, and as a result the substance undergoes a state change.

2. Draw the particle motion of these substances at the following pressures.

6. Predicting States of Matter p62

The temperature and pressure of a substance can affect its state of matterHow can you use the relationships between a substance's temperature and pressure to predict its state of matter?State DiagramsTo make such predictions, scientists have gathered data for various temperatures and pressures.Then, they plotted it in a graph like the state diagram of water.The state diagram is a tool developed by scientists to predict the of state a substance at certain temperatures and pressures.The y-axis of the graph (the vertical axis) shows units of pressure.The x-axis of the graph (the horizontal axis) shows units of temperature.

Looking at the chart, how is the melting point of water impacted by pressure?

The boiling point?

Melting point varies only

slightly according to pressure.

Boiling point varies

according to pressure.

What state would water be at –25°C and 125 kPa?

At 23°C and 101 kPa?

AT 95°C and 80 kPa?

SolidLiquid

Gas


7. Standard Temperature and Pressure p65

Standard temperature and pressure (STP) is a set of conditions that many scientists use.

STP conditions are 0°C (for temperature) and 101 kPa (for pressure).

Why do scientists use STP?Because the conditions in laboratories and at other locations for

study can vary, it is important for scientists to note when they take measurements that are different from STP.


Use the state diagrams to predict the states of

water, carbon dioxide, and gallium at given

conditions:

1) Water at 150 kPa and 0°C

2) Gallium at 100 kPa and 45°C

3) Carbon dioxide at 150 kPa and −75°C

4) Using the state diagram and particle motion,

explain how changes in temperature and pressure

can lead to state changes that you can observe on

a macroscopic scale.

liquid

liquid

gas

The state diagram shows the pattern of how

temperature and pressure influence the particle motion

of a substance.

This change in particle motion results in a macroscopic state change.

6. Predicting States of Matter ReviewPressure

(kPa)

Temperature

(oC)

State of Matter

(solid, liquid or

gas)

70 -15

70 25

70 110

101 -15

101 25

101 145

160 -15

160 25

160 101


What is the state of carbon dioxide at STP? gas


What is the state of gallium at STP? solid

What would you expect to happen if you held solid gallium in your hand? It would melt.

1) Provided below are three temperature ranges. In the circles provided, draw what water particles would look

like in each of these three temperature ranges at sea level. Make sure that your drawings:

• have a consistent number of particles

• correspond with the correct temperature ranges

• are labeled as solid, liquid, or gas

• indicate the movement of particles (using drawn lines or labels)

2) Provided are two diagrams showing a pump

before and after pressure is applied.

• In the left diagram, draw a model of what the

inside of the pump would look like if it is filled

with gas particles. Indicate the movement of the

particles.

• In the right diagram, draw a model of what

would happen to the same gas particles inside the

pump after pressure is applied. Indicate the

movement of the particles.

• Write two captions. In the first caption, describe

what happened to the gas particles (left diagram)

when pressure was applied. In the second caption,

make a claim about what would happen to the

same particles if extreme pressure is applied (right

diagram). Use evidence and reasoning to support

your claim.

3) Suppose NASA scientists have discovered a new planet that they

wish to make suitable for human life. Their first goal is to cover large

sections of the planet’s surface with water. However, they have noticed

that the planet’s northern hemisphere has extremely high pressure

and extremely low temperature. Conversely, they observed that the

planet’s southern hemisphere has extremely low pressure and

extremely high temperature. The figure provided below summarizes

the planet’s unique conditions.

As a junior scientist for NASA, you have been asked to write a one to

two paragraph report that explains what would happen to any liquid

water brought to the planet’s northern and southern hemispheres, and

why. The report should focus on behaviors seen only at the particle

level. Your report should be appropriate for a formal audience and the

following vocabulary:

WORD BANK

Gas

Liquid

Pressure

Solid

State of matter

Temperature

matter lesson 4: motion of particles

Documents