Alkali metal salts
Rule: Salts of Group I elements are soluble, including Li⁺, Na⁺, K⁺, Cs⁺, and Rb⁺.
Exceptions: Rare.

Ammonium salts
Rule: Salts containing ammonium ion (NH₄⁺) are also soluble.

Nitrate salts
Rule: Salts containing nitrate ion (NO₃^-) are soluble.

Halide salts
Rule: Salts of Group VII elements are soluble, including Cl^-, Br^-, and I^-.
Exceptions: Halide salts of silver, lead(II), and mercury(I) are insoluble, including AgCl, PbBr₂, and Hg₂Cl₂.

Sulfate salts
Rule: Sulfate salts are soluble.
Exceptions: Sulfate salts BaSO₄, PbSO₄, Ag₂SO₄, and CaSO₄ are insoluble.

Frequently INSOLUBLE salts

Carbonate salts
Rule: Carbonates are frequently insoluble, including Group II carbonates CaCO₃, SrCO₃, and BaCO₃ and others FeCO₃ and PbCO₃.

Chromate salts
Rule: Chromate salts are frequently insoluble, including PbCrO₄ and BaCrO₄.
Exception: Group I chromate salts are soluble.

Phosphate salts
Rule: Phosphates are often frequently insoluble, including Ca₃(PO₄)₂, Ag₂PO₄.

Fluoride salts
Rule: Fluoride salts are frequently insoluble, including BaF₂, MgF₂ and PbF₂.
Exception: Group I fluoride salts are soluble.

Largely INSOLUBLE salts

Silver salts
Rule: Silver salts are insoluble.
Exceptions: Silver salts AgNO₃ and Ag(C₂H₃O₂) are soluble.

Hydroxide salts
Rule I: Hydroxide salts of Group II elements are slightly soluble, including Ca(OH)₂, Sr(OH)₂, and Ba(OH)₂.
Rule II: Hydroxide salts of transition metals are insoluble, including Fe(OH)₃, Al(OH)₃, and Co(OH)₂.
Exceptions: Hydroxide salts of Group I elements are soluble.

Sulfide salts
Rule: Sulfide salts of transition metals are insoluble, including CdS, FeS, ZnS, Ag₂S. Arsenic, antimony, bismuth, and lead sulfides are also insoluble.