Atoms can chemically combine to form molecules. These molecules are also particles and cannot be separated into their atoms by physical means. In this lesson we study the way in which these particles react by using the particle model of matter.
Using the model of matter we are going to describe the three classic states of matter that we find namely solids, liquids and gases and their behaviours when their states change.
When a substance changes from a solid to a liquid to a gas we say that a change of state has taken place. In this lesson we learn about what happens when substances change from one state to next and how they gain or lose energy.
All matter has density, mass and volume. We are going to look at these characteristics in more detail including the formula that we can use to find density.
