States of MatterChapter 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 cubeLiquid:

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 cubeLiquid: hot chocolateGas:

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 cubeLiquid: hot chocolateGas: steam

ParticlesAll matter is made of tiny particles called atoms

and molecules. How the particles move determines whether an

object is solid, liquid, or gasParticles are attracted to each other, but the

faster the move, the more they can overcome their attraction.

SolidsSolids 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 SolidsCrystalline solid – have an orderly, three-

dimensional arrangement of particlesRepeating patterns of rows.Examples – iron, diamond, ice

Kinds of SolidsAmorphous – particles with no special

arrangementNo patternExample – glass, rubber, wax

LiquidsLiquids – 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 LiquidsSurface 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 LiquidsViscosity

A liquid’s resistance to flowA stronger attraction between particles = higher

viscosity = slower flow

Which has a higher viscosity: Italian dressing or ranch?

GasesGases 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 GasesSection 2

TemperatureTemperature 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.

TemperatureA 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.

VolumeWe 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!

PressurePressure 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 BehaviorTemperature, pressure, and volume are linked.Changing one factor affects the other two.

Boyle’s LawBoyle’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 LawThis means that as the pressure

increases, the volume decreases by the same amount.

Charles’s LawCharles’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 LawThis means that as volume increases,

temperature increases.

Changes of StateSection 3

Changes of StateALL 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.

MeltingChange of state from solid

to liquidEnergy is added Adding energy to a solid

increases the temperature of the solid, making the particles move faster.

Melting PointWhen 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?

FreezingFreezing 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 PointWhen 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 PointDoes the water in the ice cube tray turn into ice

all at once? Why or why not?

EvaporationEvaporation 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.

EvaporationThink 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.

BoilingEvaporation 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 PointThe 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 PressureWater 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

CondensationCondensation 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.

SublimationSublimation 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.