States of MatterChapter 3

Material on Midterm

How do materials feel as they change state?

Vanishing act

Objectives◦ Describe the properties shared by particles of all

matter◦ Describe three states of matter◦ Explain the differences between the states of

matter

Section 1: Three States of Matter

What are states of matter?◦ The States of matter are the physical forms in

which a substance can exist Solid Liquid Gas

Section 1: Three States of Matter

Particles of matter◦ Matter is made of small particles called atoms and

molecules◦ Always on the move◦ How they interact with each other determines

their state of matter

Section 1: Three States of Matter

What is a solid?◦ A solid is the state of matter that has a definite

shape and volume

◦ Particles smooshed together◦ Can only vibrate—stuck in place

Section 1: Three States of Matter

Types of solids◦ Crystalline solids have a orderly, 3D arrangement

in a repeating pattern Ice, diamond, iron

◦ Amorphous solids have no special arrangement Glass, rubber, wax

Section 1: Three States of Matter

What is a liquid?◦ A liquid is the state of matter than has a definite

volume but takes the shape of its container

◦ Little space in between particles◦ Can slide past another

Section 1: Three States of Matter

Liquid characteristics◦ Surface tension is a force that acts on the

particles at the surface of a liquid

◦ Viscosity is a liquid’s resistance to flow

Section 1: Three States of Matter

What is a gas?◦ A gas is the state of matter that has no definite

shape or volume

◦ Molecules move super fast◦ Not really held together at all

Section 1: Three States of Matter

Other States/Phases Plasma is the most common state of matter in the universe (99%).

It is a highly charged (ionized) gas.

Present in stars.

Bose-Einstein Condensate – at very low temperatures (near -273°C) atoms behave as though they were a single particle.

Check it out

State of Matter Definite Shape? Definite Volume?

Solid

Liquid

Gas

Section 1: Three States of Matter

Section Review◦ Please answer the objectives on your objective

summary sheet

1. Describe the properties shared by particles of all matter

2. Describe three states of matter

3. Explain the differences between the states of matter

Section 1: Three States of Matter

Objectives:◦ Describe the three factors that affect how gases

behave◦ List the variables involved in Boyle’s law and

Charles’s law◦ Predict how a change in pressure or temperature

will affect the volume of a gas

Section 2: Behavior of Gases

What factors affect how gases behave?◦ Temperature

◦ Volume

◦ Pressure

Section 2: Behavior of Gases

Temperature◦ Temperature is a measure of how fast the

particles in an object are moving The faster the particles move, the more energy they

have

Increase temperature….increase pressure Increase temperatures…increase volume

Section 2: Behavior of Gases

Volume◦ Volume is the amount of space that an object

takes up

◦ Volume of a gas depends on its container

◦ Decrease volume…increase pressure…pop!◦ Increase volume…decrease pressure

Section 2: Behavior of Gases

Pressure◦ Pressure is the amount of force exerted on a

given area of surface

◦ The more particles…the more pressure

Section 2: Behavior of Gases

Section 2: Behavior of Gases

Gas behavior laws◦Boyle’s Law

Involves volume and pressure

◦Charles’s Law Involves temperature and volume

Section 2: Behavior of Gases

Boyle’s Law

Section 2: Behavior of Gases

Boyle’s Law

Section 2: Behavior of Gases

What is Boyle’s Law?◦ Boyle’s Law states that a fixed amount of gas at

a constant temperature, the volume of a gas is inversely related to the pressure Inversely = opposite

So… As pressure increases, volume decreases As pressure decreases, volume increases

Section 2: Behavior of Gases

Charles’s Law

Section 2: Behavior of Gases

Charles’s Law

Section 2: Behavior of Gases

What is Charles’s Law?◦ Charles’s Law states that for a fixed amount of

gas at a constant pressure, the volume of gas changes in the same way that the temperature changes

◦ So… As temperature increases, volume increases As temperature decreases, volume decreases

Section 2: Behavior of Gases

Charles Law – soap

Charles Law - Egg

Section Review◦ Please answer the objectives on your objective

summary sheet

1. Describe the three factors that affect how gases behave

2. List the variables involved in Boyle’s law and Charles’s law

3. Predict how a change in pressure or temperature will affect the volume of a gas

Section 2: Behavior of Gases

Objectives◦ Describe how energy is involved in changes of

state◦ Identify phase changes as endothermic or

exothermic◦ Describe what happens during melting and

freezing◦ Compare evaporation and condensation◦ Explain what happens during sublimation and

deposition◦ Identify the two changes that can happen when a

substances loses or gains energy◦ Interpret a phase change(heating curve) diagram

Section 3: Changes of State

A change of state is the change of a substance from one physical form to another

Section 3: Changes of State

The six changes of state◦ Melting (SL)◦ Freezing (LS)

◦ Evaporation (LG)◦ Condensation (GL)

◦ Sublimation (SG)◦ Deposition (GS)

Section 3: Changes of State

We can either add or remove energy to get changes of state

If we add, we call it endothermic

If we remove, we call it exothermic

Section 3: Changes of State

Melting is the change of state from a solid to a liquid◦ Adding energy to a solid increases its energy◦ Particles move faster, move away from each other

The melting point is the temperature at which a substance changes from a solid to a liquid

Section 3: Changes of State

Item Melting temperature (C)

State of matter at room temperature (25C)

Water 0 C

Table salt 801 C

Nitrogen -210 C…-159C boiling

Freezing is the change of state from a liquid to a solid◦ We remove energy—molecules slow down◦ The freezing point is the temperature at which

this happens

Section 3: Changes of State

Evaporation is the change of a substance from a liquid to a gas◦ We add energy—molecules speed up◦ Does not have to have bubbles◦ Can occur just at the surface

Boiling is the change of a liquid to a gas (vapor) throughout the whole liquid

Section 3: Changes of State

Condensation is the change of state from a gas to a liquid◦ We remove energy—molecules slow down◦ Condensation point is the temperature at which a

gas becomes a liquid Same as boiling point

Section 3: Changes of State

Sublimation is the change of state from which a solid changes directly into a gas◦ We add a LOT of energy—molecules speed up a

lot

◦ Dry ice

Section 3: Changes of State

Change of temperature versus change of state◦ When energy is added…

Either the temperature changes OR the state changes

Not both!

Section 3: Changes of State

Section 3: Changes of State

When you add heat to a solid…◦ …the temperature increases until the melting

point You still add heat…

◦ …the temperature stays while the solid melts You now add heat to a liquid…

◦ …the temperature increases until the boiling point You still add heat…

◦ …the temperature stays while the liquid boils You now add heat to a gas…

◦ …the temperature will just keep increasing!

Section 3: Changes of State

Section 3: Changes of State

Section 3: Changes of State

State change Starting state

Ending state

Energy added or removed

Endothermic or exothermic

Melting

Freezing

Evaporation

Condensation

Sublimation

Deposition

Section 3: Changes of State

Section Review◦ Please answer the objectives on your objective summary

sheet

1. Describe how energy is involved in changes of state

2. Identify phase changes as endothermic or exothermic

3. Describe what happens during melting and freezing

4. Compare evaporation and condensation

5. Explain what happens during sublimation and deposition

6. Identify the two changes that can happen when a substances loses or gains energy

7. Interpret a phase change(heating curve) diagram

Section 3: Changes of State