How they move depends on the state the matter is in. In solids, such as ice, the particles are tightly packed together in a fixed orderly arrangement.

They vibrate in place, but do not move freely from their positions.

This close packing and restricted movement result in solids maintaining a definite shape and volume. In liquids, like water, the particles are still close together, but not in a fixed arrangement.

They can move and slide past each other, which allows liquids to flow and take the shape of their container while maintaining a constant volume.

The particles in a liquid move more freely than in a solid, which is why liquids can flow.

In gases, such as water vapor, the particles are far apart and move freely in all directions.

This high speed random movement allows gases to fill the entire volume of their container, expanding or compressing based on the available space.

Gases do not have a definite shape or volume, they spread out to fill the shape and volume of their container. The difference in particle movement across the three states of matter, solid, liquid, and gas, explains the unique properties of each state, including their shape, volume, and how they respond to changes in temperature and pressure.