The arrangement of particles in solids, liquids and gases Matter in all three states is made up of particles. In a solid, the particles are closely packed in an ordered arrangement. In a liquid, the particles are loosely arranged but still close together.
In a gas, the particles are not arranged in any particular way. The particles that make up matter are constantly in motion. In a solid, the particles are closely packed in an ordered arrangement. The particles do not move around but vibrate about their fixed positions.
In a liquid, the particles move around quite fast and slide past each other. In a gas, the particles move around much faster than in a liquid. They move randomly.
The particles have empty spaces between them. The spaces contain nothing. In a solid, the particles have small spaces between them. In a liquid, the particles have small spaces between them but larger than in a solid. In a gas, the particles have very big spaces between them compared to solids and liquids.
The particles attract each other. In a solid, the forces of attraction between the particles are very strong. These forces hold the particles together. In a liquid, the forces of attraction between the particles are weaker.
So, the particles are not held together and move about. In a gas, the forces of attraction are extremely weak, so the particles move about freely. Think about a pure substance such as mercury.
It is a solid below negative 39 degrees Celsius. It is a liquid between negative 39 degrees Celsius and 357 degrees Celsius. When heated above 357 degrees Celsius, it turns into a gas. The particles that make up mercury when mercury is a gas a liquid or a solid are exactly the same. Only the arrangement of the particles, the forces between them, the empty spaces between them and the speed of the particles are different.