In the example below the structure of an Explanation is seen in:

1. Introduce the topic, event or process to be explained

2. Clearly shows each step in the event or process

3. Provides explanation at each stage or change in the event or process

The Particle model is used to explain either single atoms such as gold or Helium, or molecules such as water (H2O). The particles of a solid liquid and gas are arranged differently and these are what give each state its properties.

Firstly particles as a solid are grouped together in a lattice. The particles have low energy and vibrate in a fixed spot. As energy (heat) is added to the system the particles begin to vibrate more until eventually they hit a melting point where they can separate and move around forming a liquid. The ability of particles to move around each other is what allows a liquid to have a fixed volume but not a fixed shape. Then as more energy is added to the system the particles begin to move around faster until they hit the evaporation point forming into a gas. At this point particles are moving around independently of each other. This is why gasses have the property of no fixed volume and no fixed shape. These particles are able to go down in energy (cooling) as well going through the process of condensation and freezing.