hexaaquacalciumII

Hexaaquacalcium(II) is the chemical compound with the formula [Ca(H2O)6]2+. It is a coordination complex where a central calcium ion, in its +2 oxidation state, is surrounded by six water molecules. The water molecules act as ligands, donating electron pairs to the calcium ion to form coordinate covalent bonds. This complex is often encountered in aqueous solutions of calcium(II) salts.

In aqueous solution, calcium ions do not exist as bare ions but are hydrated. The hexaaquacalcium(II) ion is the predominant species formed when calcium(II) salts dissolve in water. The positive charge of the calcium ion is balanced by the negative ends of the polar water molecules. The structure is octahedral, with the six water molecules arranged around the calcium ion.

The hexaaquacalcium(II) ion is colorless and odorless. It is a key species in many chemical and biological processes involving calcium. While often represented simply as Ca2+(aq), the coordinated water molecules are integral to its behavior and interactions in solution. The stability of the hexaaqua complex is influenced by factors such as temperature and the presence of other ions.