Hydrated ionic compound
Hydrated ionic compounds are those ionic compound
Ionic compound
In chemistry, an ionic compound is a chemical compound in which ions are held together in a lattice structure by ionic bonds. Usually, the positively charged portion consists of metal cations and the negatively charged portion is an anion or polyatomic ion. Ions in ionic compounds are held together...

s which contain water
Water is a chemical substance with the chemical formula H2O. A water molecule contains one oxygen and two hydrogen atoms connected by covalent bonds. Water is a liquid at ambient conditions, but it often co-exists on Earth with its solid state, ice, and gaseous state . Water also exists in a...

A molecule is an electrically neutral group of at least two atoms held together by covalent chemical bonds. Molecules are distinguished from ions by their electrical charge...

s inside their crystal lattice. The water is not chemically bonded
Chemical bond
A chemical bond is an attraction between atoms that allows the formation of chemical substances that contain two or more atoms. The bond is caused by the electromagnetic force attraction between opposite charges, either between electrons and nuclei, or as the result of a dipole attraction...

 to the crystal in any way, and may be driven off by heating the hydrated compound.

First system

  • The ionic compound must be named using the proper rules for naming ionic compounds.
  • The correct Greek prefixes must be added to the term "hydrate" as to indicate the number of water molecules per formula unit. Example: Monohydrate(one), Dihydrate(two), Trihydrate(three) etc.

  • To write the chemical formula; write the ionic compound then write a "dot" followed by "H2O" with the number corresponding to the prefix attached to the "hydrate" from the "word" equation. Example(s):
  • ZnCl2 • 6H2O is zinc chloride hexahydrate
  • Ba(OH)2 • 8H2O is barium hydroxide octahydrate

Second system

Naming prefixes include:

If there is no water, the prefix is anhydrous.
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