Particle Arrangement: Particles remain close together and touching, but they lack the long-range order of a solid, existing in a random, disordered arrangement.
Motion: Particles have enough kinetic energy to slide past one another, allowing liquids to flow and take the shape of the bottom of their container while maintaining a fixed volume.
Density: The density of a liquid is typically very similar to its solid form (with water being a notable exception) because the particles remain in close contact.
Particle Arrangement: Particles are very far apart, typically separated by distances ten times greater than their own diameter, meaning they occupy only a tiny fraction of the total volume.
Motion: Particles move at high speeds in random straight-line paths, colliding with each other and the walls of the container to exert pressure.
Compressibility: Due to the vast empty space between particles, gases are highly compressible and will expand to fill any available volume completely.
| Property | Solid | Liquid | Gas |
|---|---|---|---|
| Shape | Fixed | Takes shape of container | Fills container |
| Volume | Fixed | Fixed | Variable |
| Density | High | High | Low (approx. 1/1000th) |
| Compressibility | Negligible | Negligible | High |
Particle Diagrams: When drawing or identifying states, ensure solids show a regular grid, liquids show touching but disordered particles, and gases show large gaps with motion arrows.
Explaining Pressure: Always link gas pressure to the frequency and force of particle collisions with the container walls; increasing temperature increases particle speed, leading to more frequent/forceful collisions.
Density Units: Be careful with unit conversions; is equivalent to . Always check if the volume needs to be calculated from dimensions () before finding density.
Common Pitfall: Do not assume particles in a liquid are far apart; they are nearly as close as in a solid. The primary difference is their ability to move relative to one another.
