Hydrates are inorganic salts "containing water molecules combined in a definite ratio as an integral part of the crystal" that are either bound to a metal center or that have crystallized with the metal complex.
Os hidratos son sales inorgánicos que "conteñen moléculas de auga combinadas nunha proporción definida como parte integrante dun cristal", que poden estar unidas a un centro metal ou que cristalizaron co complexo metal.