Solids have a fixed shape and a fixed volume. Liquids have a fixed volume, but no fixed shape. Gases have neither a fixed volume nor a fixed shape. Solids cannot be compressed. The molecules have an ordered arrangement. Liquid - Molecules will flow or glide over one another, but stay toward the bottom of the container. Motion is a bit more random than that of a solid. They have enough kinetic energy to slip out of the ordered arrangement of a solid.