When metal hydroxides dissolve in water, they form metal cations and hydroxide anions. This process is called dissociation.

Here's a simplified explanation:

* Metal hydroxides have the general formula M(OH)_n, where M represents the metal and n is the charge of the metal ion.

* When they dissolve in water, the metal-hydroxide bond breaks, releasing the metal cation (Mⁿ⁺) and the hydroxide anion (OH^-) into the solution.

Example:

Sodium hydroxide (NaOH) dissolves in water to form sodium ions (Na⁺) and hydroxide ions (OH^-).

NaOH(s) → Na⁺(aq) + OH^-(aq)

Important Note: Not all metal hydroxides are soluble in water. Some are only slightly soluble or insoluble. The solubility of metal hydroxides depends on the metal involved.