How close the particles are to each other in state?

In a solid state, the particles (atoms, molecules, or ions) are held together by strong intermolecular forces and are packed tightly together in a regular, repeating arrangement. This results in the particles being very close to each other, with little to no space between them. The particles in a solid are so close that they can vibrate but cannot move past each other. This is why solids have a definite shape and volume.

In a liquid state, the particles are still held together by intermolecular forces, but these forces are weaker than in a solid. This allows the particles to move more freely and to take on the shape of their container. The particles in a liquid are close together, but not as close as in a solid. They can move past each other, but they are still attracted to each other.

In a gas state, the particles are very far apart from each other and have very little intermolecular force between them. This allows the particles to move very freely and to take on the shape and volume of their container. The particles in a gas are so far apart that they can move past each other without colliding very often.