What’s the Deal With Chemicals That End in ·6H₂O?

For all you out there making metal oxide aerogels using epoxide-assisted gelation, you’ll notice many of the metal salts you use end in a dot with a number and then H₂O. For those of you who could use a bit of clarification, this means that water molecules are attached to the metal ion as ligands, where each water molecule donates electron density from the oxygen into a d orbital of the metal ion. Check out this page for more details.