Chapter 2: States of Matter

Solid: Definite shape and volume; molecules are closely packed together in a fixed arrangement.

Liquid: Definite volume but takes the shape of its container; molecules are closely packed but can flow past one another.

Gas: No definite shape or volume; molecules are far apart and move freely, allowing the gas to expand and fill its container.

Plasma: A state of matter consisting of ionized gases with free-moving charged particles; it occurs at extremely high temperatures and is found in stars, including the sun.