Physical state at room temperature (25 oC) and standard atmospheric pressure:
Under these conditions, the physical state of a substance is determined mainly by its chemical bond characteristics.
Intermolecular forces of attraction:
- Ionic compounds have strong electric charges holding the ions together 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.
Within an atom, these forces are called weak forces, because they are much weaker than chemical bonds between atoms. Weak forces involve the attraction of the electrons of one atom for the protons of another atom.
When weak forces interact between molecules, they are known as van der Waals forces, named for Johannes Diderik van der Waals.
The Kinetic Theory