London dispersion forces occur between nonpolar molecules and are extremely weak.
Dipole-dipole forces are between polar molecules, and since polar molecules have slight charges, their force is more similar to ions, giving them a moderately strong bond. Hydrogen bonds occur when hydrogen is directly bonded to Flourine, Nitrogen, or Oxygen. Because of the extreme polarity if these molecules (e.g. water), hydrogen bonds are the strongest dipole-dipole bonds.
Ionic crystallization packs ions into a crystal, and those are extrao