States of Matter
Chapter 2
Three States of Matter
Section 1
 Identify the three states of matter in this scenario:
 You come inside from shoveling some snow. You’re cold,
so you make some hot chocolate. You take a sip from the
nice, steamy cup, but it burns your lip. You add an ice
cube so you can drink it sooner.
 Identify the three states of matter in this scenario:
 You come inside from shoveling some snow. You’re cold,
so you make some hot chocolate. You take a sip from the
nice, steamy cup, but it burns your lip. You add an ice
cube so you can drink it sooner.
 Solid:
 Identify the three states of matter in this scenario:
 You come inside from shoveling some snow. You’re cold,
so you make some hot chocolate. You take a sip from the
nice, steamy cup, but it burns your lip. You add an ice
cube so you can drink it sooner.
 Solid: ice cube
 Liquid:
 Identify the three states of matter in this scenario:
 You come inside from shoveling some snow. You’re cold,
so you make some hot chocolate. You take a sip from the
nice, steamy cup, but it burns your lip. You add an ice
cube so you can drink it sooner.
 Solid: ice cube
 Liquid: hot chocolate
 Gas:
 Identify the three states of matter in this scenario:
 You come inside from shoveling some snow. You’re cold,
so you make some hot chocolate. You take a sip from the
nice, steamy cup, but it burns your lip. You add an ice
cube so you can drink it sooner.
 Solid: ice cube
 Liquid: hot chocolate
 Gas: steam
Particles
 All matter is made of tiny particles called atoms and
molecules.
 How the particles move determines whether an object
is solid, liquid, or gas
 Particles are attracted to each other, but the faster the
move, the more they can overcome their attraction.
Solids
 Solids have a definite shape and volume.
 Particles are very close together, and there is a strong
attraction between them.
 Each particle
vibrates in place,
but is locked in
position by the
particles around it.
Kinds of Solids
 Crystalline solid – have an orderly, three-dimensional
arrangement of particles
 Repeating patterns of rows.
 Examples – iron, diamond, ice
Kinds of Solids
 Amorphous – particles with no special arrangement
 No pattern
 Example – glass, rubber, wax
Liquids
 Liquids – have a definite volume, but not a definite
shape.
 Liquids take the shape of their containers.
 The particles in a liquid
move fast enough to
overcome some of their
attraction, so liquids can
flow.
Properties of Liquids
 Surface Tension
 A force that acts on particles at the surface of a liquid.
 A liquid with a high surface tension forms rounded drops.
A liquid with a low surface tension forms flat drops.
Properties of Liquids
 Viscosity
 A liquid’s resistance to flow
 A stronger attraction between particles = higher viscosity
= slower flow
 Which has a higher viscosity: Italian dressing or ranch?
Gases
 Gases have no definite shape or volume.
 Gas particles move very quickly and can break away
from one another.
 Gases are compressible. The amount of space in
between particles can change.
Behavior of Gases
Section 2
Temperature
 Temperature is the measure of how fast the particles in
an object are moving.
 The higher the temperature, the faster the particles are
moving.
 The faster the particles are moving, the more energy
they have.
Temperature
 A gas with a higher temperature will expand more.
 If you fill a balloon in cold weather, it will need more
gas to be full. If it suddenly gets warm, it may pop
because the gases expand.
Volume
 We know that volume is how much space an object
takes up.
 Because gases particles can move and spread out,
their volume depends on their container.
 It is possible to make balloon animals
because the gases in the balloon can
be compressed. A water balloon would
just explode!
Pressure
 Pressure is the amount of force on an area.
 In gases, the pressure is the number of times the gas
particles hit the inside of their container.
 Why is the pressure of a basketball greater than a
beach ball?
 There are more particles of gas in a basketball than in
a beach ball. Basketballs are usually filled with a
pump, while beach balls are generally filled by blowing
them up.
Gas Behavior
 Temperature, pressure, and volume are linked.
 Changing one factor affects the other two.
Boyle’s Law
 Boyle’s Law – for a fixed amount of gas
at a constant temperature, the volume of
a gas is inversely related to the pressure.
Boyle’s Law
 This means that as the pressure
increases, the volume decreases by the
same amount.
Charles’s Law
 Charles’s law – for a fixed amount of gas at a constant
pressure, the volume of the gas volume and
temperature change in the same direction.
Charles’s Law
 This means that as volume increases, temperature
increases.
Changes of State
Section 3
Changes of State
 ALL changes of state are physical changes.
 To change an state of matter, you must add or remove
energy.
 Water is the only substance that can be found in all
three states at normal surface temperature and
pressure.
Endothermic vs Exothermic
 Endothermic – energy is gained as the substance
changes state
 Exothermic – energy is removed as the substance
changes state.
Melting
 Change of state from solid to
liquid
 Energy is added
 Adding energy to a solid
increases the temperature of
the solid, making the particles
move faster.
Melting Point
 When a solid melts, particles must break some of the
attraction that holds them together.
 The point where they break is the melting point.
 Melting point is a physical property – it could help you
identify a substance.
Common Melting Points
 What is the melting point of water?
Freezing
 Freezing is the change of
state from a liquid to a solid.
 Energy is removed.
 Removing energy makes the
particles begin to lock in place.
 Freezing point is the time
when the liquid turns into a
solid
Freezing Point
 When you put an ice cube tray in the freezer, does it
freeze as soon as it touches the cold air? Why or why
not?
Freezing Point
 Does the water in the ice cube tray turn into ice all at
once? Why or why not?
Evaporation
 Evaporation is the change of state from liquid to gas.
 Sweat is mostly water. When you sweat, the water
evaporates. You feel cooler because your body is
transferring energy to the water.
Evaporation
 Think about it: In our country, when it is hot we usually
wear skimpy clothing – bathing suits, shorts, tank tops,
etc. In other parts of the world with hot climates,
people wear long, loose, light-colored clothing. In hot
parts of the world, people also tend to eat spicy food.
Brainstorm why this might be a more effective way to
keep cool.
Boiling
 Evaporation occurs at the surface of a liquid, while
boiling changes a liquid to a gas all throughout the
liquid.
 Boiling creates bubbles. The pressure inside the
bubbles is called vapor pressure.
 Boiling occurs when the vapor pressure equals
atmospheric pressure.
Boiling Point
 The boiling point is the temperature (and pressure) at
which a liquid turns to gas.
 This requires an input of energy, in order to break the
bond of liquid particles.
 What is the boiling point of water?
 What is the boiling point of water?
212°F or 100°C
Atmospheric Pressure
 Water boils at 100°C only at sea level. Because boiling
depends on atmospheric pressure, at higher altitudes,
the boiling point is lower.
 Ex. In Denver (in the Rocky Mountains) water boils at
95°C
Condensation
 Condensation is the change of state from a gas to a
liquid.
 Condensation is the reverse of evaporation, so the
condensation point occurs at the same temperature as
the boiling point.
 Condensation releases energy.
Sublimation
 Sublimation is when a solid changes directly into a gas.
 This requires a high energy input to break the solid
bonds.
 Not highly common. Carbon dioxide and arsenic often
sublimate – it is difficult to find them in liquid form.
Temperature and State
Change
 Temperature is related to the speed of the object’s
particles.
 Temperature does not change until state change is
complete.