Particle Model and Physical Properties

Particle Model and Physical Properties

Particle Model

Most physical changes can be understood by using the particle model.

The particle model is a simplified representation of solids, liquids and gases.

It can explain some but not all of their properties.

Particle Model

The particle model assumes that all forms of matter (solids, liquids and gases) are made up of invisible, ball- like particles that are:

• Hard, incompressible and indivisible

• Attracted to each other

• Constantly moving

Particle Model

​Solids	​Liquids	​Gases
Attraction between particles binds them tightly and rigidly together.	Particles are packed tightly together,​ but are not stuck to each other.	Particles are not stuck together and there is a large space between them.​
Incompressible and hold their own shape. Vibrate on the spot with temperature.	Incompressible but flow to take up shape of the container. Particles vibrate and move freely.​	​Highly compressible. Particles move in straight lines until they collide with another gas particle or the side of the container so they fill container.

Categorize

Options (8)

Egg White

Yoghurt

Dry Ice

Methane

Cloud

Smoke

Propane

Organise the images into their correct categories,

Solid

Liquid

Gas

Freezing / Melting

We know what freezing and melting are. Freezing is the change from liquid to solid and melting is the change from solid to liquid. But what is happening to the particles?

Have a think to yourself and discuss with the person next to you. Remember that heat is the amount of kinetic energy (movement) something has.

Open Ended

What is happening to the particles when something melts?

Evaporation / Condensation

Similar to solids becoming liquids, evaporation occurs when the amount of kinetic energy (temperature) increases and the bonds between particles break. They end up moving so fast that the ones of the surface can break free.

Changing States

Changing states depends on the amount of kinetic energy between particles.

More energy and the bonds break free, less energy and the particles stick back together.

Multiple Choice

Gases consist of particles that:

• Are strongly attracted to each other

• Have a regular arrangement

• Are packed close together

• Are very far apart

Multiple Select

Which three of the following statements explains why solid particles have a definite shape?

• They are packed together very tightly.

• They are arranged in a regular way.

• There is a strong force of attraction between the particles.

• They can be compressed.

Multiple Choice

Which one of the following is not a property of a gas?

• Can be compressed

• No definite shape

• Definite mass

• Definite volume

Multiple Choice

When water vaporises at room temperature, it changes into:

• Ice

• Fog

• Steam

• Water Vapour

Activity

1. Everyone spread around the room.

2. I am going to spray some perfume and you must raise your hand when you smell it.

3. Answer the questions below:

• Describe what happened.

• Explain why you think it happened.