Chapter 7.1

States of Matter

In this chapter...

• we will learn about matter and different states of matter, many of which we are already familiar with!

• Learning about Kinetic Molecular Theory will help us to understand how particles in matter behave when we add or remove energy.

What is Matter???

• Matter is anything with mass and volume.

• The earth and everything around you is composed of matter in different forms.

Examples of matter: glass, oxygen, water, you!

Mass and Volume

• Mass is the quantity (amount) of matter a substance has in it!

• Volume is the amount of space taken up by an object or substance.

Example:

grams (g),kilograms (kg)

millilitres (mL),litres (L),

cubic centimeters (cm3)

Measured in:

VS

Bowling ballBeach ball

More MASS More VOLUME

Particles Make Up MASS

• Matter is made up of very small particles (atoms and molecules).

• These particles are too small to see with our eyes or a light microscope

3 States of Matter

• We are most familiar with three states:– Solid, liquid and gas

• Solids have a definite shape and volume.Particles are tightly packed together and remain in close contact to one another. The particles vibrate.

3 States of Matter

• Liquids have a definite volume but NOT a definite shape.

• The particles change their position by a ‘slip and slide’ motion past one another but they remain in contact. Due to the fluid nature of liquids, they will take the shape of the container that holds them.

“Slip and Slide”motion

3 States of Matter• Gases do NOT have a definite volume or

shape!

• The shape and volume of a gas depends on its container or surroundings.

• The particles of a gas are spaced far apart and move quickly in all directions.

• The ability of gases to diffuse means they will fill any container.

Particle Model of Matter

• There are FOUR points to remember:(1)All matter is made up of very small

particles.(2) There are spaces between the

particles.(3)The particles are always moving.(4)The particles are attracted to each

other. The strength of attraction depends on the type of particle.

KINETIC ENERGY!!

• Kinetic energy is the energy of motion!

• Any particle that is moving has kinetic energy.

• We know that all particles in a solid, liquid and gas have movement; therefore, they ALL have kinetic energy.

All Have Kinetic Energy

Kinetic Molecular Theory

• KMT offers an explanation for how matter is affected by changes in kinetic energy.

• KMT is an expansion of the particle model of matter (first three points are the same!)

(1) All matter is made up of small particles (atoms and molecules).

(2)There is empty space between particles.(3)Particles are constantly moving and colliding.(4)Energy makes particles move. The more

energy they have, the faster they move and the farther apart they get!

INCREASE KINETIC ENERGY

Particles move faster and farther apart...

Thermal Expansion

• One of the easiest and most common ways to add energy to matter is to add heat.

• When we add heat any state of matter, KMT tells us that the particles will begin to move faster and farther apart.

Particles move apart more space between particles volume increases.

Thermal Expansion

Expansion in action....

• Imagine you fill up an air mattress in a cool place.

• When you take it to the beach on a hot day, the air inside gains kinetic energy in the heat.

• As the movement of the air particles increases and the space between them gets bigger;

• the air expands inside and pushes against the walls of the air mattress.

ENE RGY

Thermal Contraction

• Removing heat from any solid, liquid or gas will have the opposite effect of expansion.

• As we cool a substance, the kinetic energy decreases and the particles slow down their movement.

• The particles take up less space so the volume of the object decreases.

Thermal Contraction

Contraction in action...

• Put a balloon filled with air into liquid nitrogen. Liquid nitrogen is very cold (approximately -1970C)

• As soon as the balloon is immersed in the liquid, it will shrink.

• Air particles slow down and take up less space.

Before

After

Contraction and Expansion

• Thermal energy is the sum of the kinetic energy of all the particles in a substance.

• Thermal energy always flows from a substance with high thermal energy to a substance with lower thermal energy.

Ex: When you touch a hot coffee mug, thermal energy flows from the

mug to your fingers.

Heat and Temperature

• Temperature = the measure of the average kinetic energy

• Heat = the energy transferred from one material to another as a result of a difference in temperature.

Not the

same

meaning

Changes of State

• A change in state occurs when the temperature of a substance is raised or lowered.

When the temperature is raised, kinetic energy is ADDED

When the temperature is lowered, kinetic energy is REMOVED

Changes of State

Deposition

Sublimation

Solid Liquid

• When enough energy is added to a solid, the particles speed up and it MELTS.

• The point at which it melts is the melting point.

• When enough energy is removed from a liquid, the particles slow down and move closer. It becomes a solid.

Melting Point

Liquid Gas

• When enough energy is added to a liquid, the particles speed up and it evaporates.

• The point at which it becomes a gas is the boiling point.

• When gas cools back to a liquid state, this is condensation.

Boiling Point

Solid Gas

• Solid if its heated enough can go straight to gas state!– Ex: Dry Ice

• Gas can also be cooled straight to solid state!– Ex: frost on a cold

day

Sublimation

Deposition