Answer:
What is the particle model of matter?
How small are atoms and molecules?
How does the particle model of matter describe solids, liquids and gases?
How does the particle model of matter help us understand the process of diffusion?
How can materials be made to change their state?
How does the particle model of matter help us to understand changes of state in materials, such as melting, evaporation, condensation and freezing?
How are density, mass and volume related to each other?
How do the densities of solids, liquids and gases compare?
Which aspects of the particles in a given material influence the density of that material?
Why does oil float on water? Is this related to density?
How can the particle model of matter help us to understand expansion and contraction?
How does a gas exert pressure?
Is the pressure a gas exerts related to the number of gas particles? If so, how?
What happens to pressure when we change its volume and temperature?
Can you remember learning that matter can exist in three different states? What are the three states called?
Can you remember the properties of the different states of matter? Discuss this in your class. Look at the following diagram of the states of matter to help you. Remember to take some notes as you discuss in class.
Each state of matter behaves differently and the particles in each state behave differently. This diagram compares the particles in a gas, a liquid and a solid.
In this chapter we are going to review what we know about solids, liquids and gases. We are going to learn about a scientific model that can be used to describe how the particles in all three states behave. This model is called the particle model of matter and it will help us understand much more about the properties of solids, liquids and gases. Let's get started!
What is the particle model of matter?
scientific theory
phenomenon
disordered
uniform
random
reverse
controlled experiment
In the previous chapter we learnt that scientists use models when they want to describe things that are difficult to understand. We discussed a model of the atom that helped us to imagine what atoms look like.
This model of the atom shows us where the different sub-atomic particles can be found. The sub-atomic particles shown here are the proton, neutron and electron.
Theories are similar to models. They explain scientific phenomena (things and events that can be described and explained in scientific terms) using pictures and words.
What does the particle model of matter teach us?
The particle model describes matter in a very specific way. It describes four important aspects of matter:
All matter is made up of particles that are incredibly small - much too small to see with the naked eye. The particles can be atoms or combinations of atoms that are bonded.
There are forces between the particles.
The particles in matter are always moving. The more energy they have, the faster they move.
The spaces between the particles in matter are empty. You might assume that the spaces between particles are filled with air, but this is not the case. They contain nothing at all.
If you need to, turn back to chapter 1 to revise the terms atom, element, compound and molecule and how they relate.
Why is the particle model of matter so useful?
The particle model of matter is one of the most useful scientific models because it describes matter in all three states. Understanding how the particles of matter behave is vital if we hope to understand science!
The model also helps us to understand what happens to the particles when matter changes from one state to another.
The following diagram shows different changes of state, as well as which processes are the reverse of each other. Melting and freezing are the reverse processes of each other and so are evaporation (boiling) and condensation.
Under special circumstances, a solid can change directly into a gas without melting first. This process is known assublimation and its reverse (when a gas changes directly into a solid without condensing first) is called deposition.
