Particle Model

• The particle model is widely used to predict the behaviour of solids, liquids and gases
• Solids have strong forces that hold the particles close together in a fixed regular arrangement
• In solids particles do not have much energy so they can only vibrate in their fixed positions
• In liquids the particles are close together but can move past each other and form irregular arrangements
• In liquids the particles move in random directions at a low speed
• In gases there are almost no forces of attraction between the particles and they have high amounts of energy
• In gases the particles are free to move and travel in random directions at high speeds
• Changes of state are physical changes which differ from chemical changes because the material recovers its original properties if the change is reversed
• Solids melt to form liquids
• Liquids freeze to form solids
• Liquids boil or evaporate to form gases
• Gases condense to form liquids
• Solids sublimate to form gases