States of Matter

States of Matter

The three states of matter are; solid, liquid and gas. These are the three different forms that materials come in. The state, or form, of the material depends on the strength of the forces of attraction between the particles of the material. This force is determined by three things; 

• the material
• the temperature
• the pressure. 

1.1 understand the arrangement, movement and energy of the particles in each of the three states of matter: solid, liquid and gas 

Solids 

a) Solids have very strong forces of attraction between their particles, which is why they are held so closely together in fixed positions, as shown in the diagram. They form a very regular lattice arrangement.

b) The particles do not move from their positions. Solids keep a definite shape and volume at all times because of this. 

c) When heated, the particles in a solid will vibrate about their positions. This causes solids to expand slightly when heated, and can lead to the solid melting to become a liquid. 

Liquids

a) Liquids have a weaker force of attraction between it's particles than solids. The particles are randomly arranged and are able to move past each other, however they tend to stick close together, as shown in the diagram above. 

b) Liquids will always have a definite volume, but not always a definite shape. For example, if a liquid was poured into an empty container it's volume would remain the same, but the shape would not, and it would instead change to the shape of the container. 

c) The particles within a liquid are constantly moving with random motion. When heated, the pace at which these particles move increases and this causes the liquid to expand slightly. This can lead to a liquid evaporating to become a gas. 

Gases

a) Gases have a very weak force of attraction between it's particles. The particles are free to move around and are far apart, just like in the diagram above. Additionally, the particles in gases always travel in straight lines. 

b) Gases do not keep a definite shape or volume. They will fill any container they are put into.

c) Like in a liquid, the particles in a gas move constantly with random motion. When heated, the pace at which the particles travel is increased, leading the gas to either expand when heated, or to have it's pressure increased.