The collisions eventually become so great that the particles break all intermolecular forces, begin moving independently between collisions, and a change in physical state occurs. Gas - a substance whose particles have enough kinetic energy to break all intermolecular forces of attraction. The particles of a gas move independently of each other. The particles move at random because they have overcome the intermolecular forces of attraction. When a gas is raised to extreme temperatures, over 5000 o C, they have so much kinetic energy that their collisions will break electrons out of the atoms, and a change in physical state occurs.
Ionic compounds have strong electric charges holding the ions together and exist as solids.
Nonpolar molecular compounds of low molecular mass tend to be gases. Greater molecular mass and greater polarity both tend to make substances more dense, producing either liquid or solid. Weak forces involve the attraction of the electrons of one atom for the protons of another atom. When these forces interact between molecules, they are known as van der Waals forces . The hydrogen electron is attracted toward the eight protons of oxygen.