Welcome to this deck on the particle model of matter. We'll explore how everything around us is made of tiny, moving particles. You'll learn how the arrangement and energy of these particles explain the properties of solids, liquids, and gases. We will also cover key concepts like density, internal energy, and changes of state, including the required practical for measuring density.

The particle model is a simple but powerful idea. It states that all substances are made up of a huge number of tiny particles, which are constantly moving. The state of a substance – whether it's a solid, liquid, or gas – depends on how these particles are arranged and how much energy they have.

Let's start with solids. In a solid, the particles are packed very closely together in a fixed, regular pattern, often called a lattice. There are strong forces of attraction holding them in place. This is why solids have a fixed shape and volume. The particles don't stay completely still, however; they vibrate about their fixed positions.