Well, this could be 2 things, a solid or a property called density. Solids are tightly packed atoms, while Density is how packed the atoms are.
Air particales are packed very tightly together, so there is little space, BUT, just like in outer space, there is pretty much nothing in between particales. It is void. That is why there is no sound in space, there are no atoms for the sound waves to travel over
Solids
solids can diffuse but not in an easy way because they are to tightly packed together
The arrangement of particles are packed together.
packed together
tightly packed atoms
Solids, usually.
solids - tightly packed and unable to move liquids- tightly packed but able move gases- spread out and able to move
because the particle in solids are tightly packed
because the particle in solids are tightly packed
Solids are rigid and hard because they have no definite shape and volume and they're tightly packed