- Result when electronegativity differences between the atoms in a bond are large.
- Called salts or "formula units"
- Oppositely charged ions attract one another and arrange in a crystal lattice such that attractions are maximized and repulsions are minimized for greatest stability.
- Crystalline arrangements depend on type, structure and ratio of ions involved. Possible arrangements of the ions in the lattice are cubic, monoclinic, hexagonal, etc.
- When bonds break (melting, dissolving), the organized structure of the lattice is lost.
- Because the ionic bonds are so strong, we rarely have to consider the melting or evaporating of the ions. The ability of a salt to dissolve in water to form an aqueous solution is the chief concern.
- Result when electronegativity differences between the atoms in a bond are small.
- Called "molecules"
- Individual molecules have organized structures and distinct 3-dimensional shapes which are retained during changes in state such as evaporation and melting.
Molecules clump together in the condensed (liquid, solid) states due to intermolecular forces.