In some cases the solubility may be very high and a large amount of the solid may dissolve before the solution is saturated. The differency in ability to dissolve in water are large. Salts which are less soluble in water than this at room temperature are called slightly soluble salts. Metal halides are generally highly soluble. Most sulfate salts.
Metal sulfides are generally insoluble.
Solubility Product Constant Ionic compunds dissolve to the point where the solution is saturated and no more solid can dissolve. The concentration of the saturated solution is termed the solubility of the substance. In such a saturated solution, equilibrium is established. Ions will form solid in the same extent as solid dissocate and form ions. K sp is a temperature-dependent constant refering to this stage.