The unifying concept in this chapter is that forces of at traction between formula units act with varying success to overcome what would otherwise keep the units widely apart, their kinetic motions. The outcome determines the physical state of the substance, whether it's a solid, a liquid, or a gas.
Pressure alone is an important additional factor with gases.
Temperature could be listed, too, but it's related to kinetic motions. It illuminates all other topics of this chapter and most to come. Such motions oppose forces of attrac tion. The kinds and relative strengths of the electrical forces that affect molecular kinetic motions are reviewed in this chapter . The general gas laws.