Number per atom, strength, direction and electron distribution fix properties of compound Intermolecular Forces - Attraction between molecules Weaker than chemical bonds. Determine phase and solubility.
Noble gases have great stability, as evidence by reluctance to form compounds.
Octet Rule - Atoms will lose, gain, or share valence electrons to achieve electron configuration of nearest noble gas. Transition elements can often form different ions. Ionic bond is attraction between oppositely charged ions. Formula unit gives ratio in ionic crystal lattice. Subscripts represent relative numbers of ions in formula unit.