Particle Behavior

Objective: Compare particle arrangement and macroscopic shape and volume.

In a solid, particles remain near relatively fixed positions while vibrating or otherwise moving microscopically; a crystalline solid has organized structure, while amorphous solids differ. Liquids flow and take a container’s shape while maintaining approximately fixed volume over modest pressure ranges. Gases spread to fill available volume and are readily compressed because particles are widely separated relative to their sizes. These are models with exceptions and ranges, not claims that solid particles never move or liquids are perfectly incompressible. Plasma is an ionized state found in many high-energy contexts. Macroscopic state depends on temperature, pressure, composition, and intermolecular interactions.

Objective: Apply particle behavior to calculations, evidence, and specified situations.

States of matter differ in particle arrangement, motion, and interactions. Solids generally keep shape and volume; liquids keep volume while adapting shape; gases expand to the available volume and are relatively compressible. Heating changes internal energy and can change phase, but particles do not individually enlarge into the container or become different elements. A microscopic drawing is a simplified representation of dynamic three-dimensional behavior. Statements depend on conditions and material; some solids are amorphous and real substances have additional phases.