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P3 A) The Particle Model
P3 A) The Particle Model
Kinetic Particle Theory explains the properties of the 3 different states of matter; solids, liquids and gases. The particles in each of these states have different amounts of energy. However, the particles will be the same particles in each of the 3 states; for example, water is still H2O if it is ice (solid), water (liquid) or water vapour (gas). A change in state is a physical change rather than a chemical change because the substance remains the same (a chemical change is when a chemical reaction happens and the arrangement of the atoms changes). We can use particle theory to explain how particles behave in the three different states. The particles in the particle theory could be atoms, molecules or ions.
Solids
There are strong forces of attraction between the particles in a solid, which results in the particles forming a regular lattice arrangement. Solids have a fixed shape and volume and they cannot flow. This is because the particles remain in their fixed positions in the regular lattice structure. If I was to place an ice cube into an empty glass, the ice cube will keep its shape and not fill the container. The particles in a solid do not have much energy and can therefore only vibrate around their fixed positions in the regular lattice structure. As the particles gain more energy, they will vibrate more around their fixed positions.
Liquids
There are weaker forces of attraction between the particles in a liquid compared to when the particles are in a solid. The particles in a liquid are close together and they can move past each other in random directions and flow, which means that a liquid will take the shape of the container that they are put in. If I was to pour some water into a cup, the water would fill the shape of the cup. Liquids have a fixed volume – they cannot be compressed or squashed. The particles in a liquid form an irregular arrangement. The particles in liquids have more energy than in solids. As the temperature of the liquid increases, the particles have more energy, which results in the particles moving around faster.
There are weaker forces of attraction between the particles in a liquid compared to when the particles are in a solid. The particles in a liquid are close together and they can move past each other in random directions and flow, which means that a liquid will take the shape of the container that they are put in. If I was to pour some water into a cup, the water would fill the shape of the cup. Liquids have a fixed volume – they cannot be compressed or squashed. The particles in a liquid form an irregular arrangement. The particles in liquids have more energy than in solids. As the temperature of the liquid increases, the particles have more energy, which results in the particles moving around faster.
Gases
The forces of attraction between the particles in a gas is the weakest out of the 3 states. The particles in a gas are far apart and are in a random arrangement. The particles move quickly in random directions at a range of speeds. A gas will completely fill the container that they are placed in, and they can be compressed or squashed. This means that they do not have a definite shape or volume. Out of the 3 states, the particles in a gas have the most energy. As the temperature of a gas increases, the particles will have more energy, which causes them to move around faster. This causes the pressure of the gas to increase (we will look at pressure in the next section).
The forces of attraction between the particles in a gas is the weakest out of the 3 states. The particles in a gas are far apart and are in a random arrangement. The particles move quickly in random directions at a range of speeds. A gas will completely fill the container that they are placed in, and they can be compressed or squashed. This means that they do not have a definite shape or volume. Out of the 3 states, the particles in a gas have the most energy. As the temperature of a gas increases, the particles will have more energy, which causes them to move around faster. This causes the pressure of the gas to increase (we will look at pressure in the next section).
Here is a comparison of the characteristics of the particles in the 3 different states.
A Few Drawbacks of the Particle Theory Model
The particle theory model is a good model for explaining the characteristics of the particles in the 3 different states. However, it does have a few drawbacks. One drawback is that the atoms in real life are not solid spheres; instead they are atoms, molecules and ions. Also, the particle theory model does not show how strong the forces are between each of the particles; it does not explain why the forces between the particles are stronger for certain substances (such as giant ionic compound like sodium chloride) and weaker for other substances (such as simple molecular substances like water).
The particle theory model is a good model for explaining the characteristics of the particles in the 3 different states. However, it does have a few drawbacks. One drawback is that the atoms in real life are not solid spheres; instead they are atoms, molecules and ions. Also, the particle theory model does not show how strong the forces are between each of the particles; it does not explain why the forces between the particles are stronger for certain substances (such as giant ionic compound like sodium chloride) and weaker for other substances (such as simple molecular substances like water).