Solids, liquids and gases
The three The three forms in which a substance can exist (solid, liquid, and gas). are solid, liquid and gas. The The scientific theory used to explain the properties of solids, liquids and gases. It involves the arrangement and movement of the particles in a substance. represents A general term for a small piece of matter. For example, protons, neutrons, electrons, atoms, ions or molecules. by small, solid spheres. It describes the arrangement, movement and The capacity of a system to do work or the quantity required for mechanical work to take place. Measured in joules (J). For example, a man transfers 100 J of energy when moving a wheelbarrow. of particles in a substance. The model can be used to explain the A description of the appearance of a substance or how it acts without involving chemical reactions. For example, state, melting point, conductivity, etc. of solids, liquids and gases.
Learn more on states of matter in this podcast.
Listen to the full series on BBC Sounds.
Particle arrangement and movement
The table below shows a comparison of the same substance in three different states.
The particles in the diagrams could be The smallest part of an element that can exist., A collection of two or more atoms held together by chemical bonds. or Electrically charged particle, formed when an atom or molecule gains or loses electrons. depending on the type of substance, eg ionic compounds, small molecules, giant molecules, and metals.
Explaining properties
A single particle does not have the properties of the material it is part of. The properties of a substance are the properties of a huge number of particles together.
Solids:
- have a fixed shape and cannot flow, because their particles cannot move from place to place
- cannot be Made smaller by squeezing together. (squashed), because their particles are close together and have no space to move into
Liquids:
- flow and take the shape of their container, because their particles can move around each other
- cannot be compressed, because their particles are close together and have no space to move into
Gases:
- flow and completely fill their container, because their particles can move quickly in all directions
- can be compressed, because their particles are far apart and have space to move into
