The particles of a gas are not packed closely together. In fact, they are spread far apart with lots of empty space between them. This is the key difference between gases and solids or liquids.

Here's a breakdown:

* Solids: Particles are tightly packed and vibrate in fixed positions.

* Liquids: Particles are closer together than in gases but can move around each other.

* Gases: Particles are far apart and move freely in all directions.

This loose arrangement of particles in gases allows them to:

* Expand to fill any container: Gas particles spread out to fill the entire available space.

* Be highly compressible: The large spaces between particles allow them to be squeezed closer together.

* Have low density: The spread-out nature of gas particles means they have a lower density compared to solids and liquids.