Oxosalts

Oxosalts are salts whose anions derive from oxoacids (acids that contain oxygen) after the acidic hydrogen atoms are removed.

Traditional nomenclature

In traditional (common) nomenclature the oxoacid ending -ic becomes -ate and -ous becomes -ite when forming the salt name. The metal name is stated first; indicate the metal oxidation state using Roman numerals when necessary.

Examples:

• Na₂SO₄: sodium sulfate (from H₂SO₄, sulfuric acid)
• KNO₃: potassium nitrate (from HNO₃, nitric acid)
• CaCO₃: calcium carbonate (from H₂CO₃, carbonic acid)
• NaClO₄: sodium perchlorate (from HClO₄, perchloric acid)
• KClO₃: potassium chlorate (from HClO₃, chloric acid)
• Fe₂(SO₄)₃: iron(III) sulfate (from H₂SO₄, sulfuric acid)
• KMnO₄: potassium permanganate (from HMnO₄, permanganic acid)

Additive (systematic) nomenclature

Additive systematic names use prefixes to indicate the number or type of oxygen-containing groups in the anion (mono-, di-, tri-, tetra-, etc.), and name the anionic unit followed by the metal (and multiplicity if needed).

Examples:

• KNO₃: trioxonitrate of potassium
• CaSO₄: tetraoxosulfate of calcium
• NaClO: oxochlorate of sodium
• Ca(ClO)₂: bis(oxochlorate) of calcium
• Fe₂(SO₄)₃: tris(tetraoxosulfate) of diiron
• AgNO₃: trioxonitrate of silver

Compositional systematic nomenclature

Compositional names indicate the number of oxygen atoms and the overall charge of the anion (e.g., trioxonitrate(1-)), followed by the metal and its oxidation state when appropriate.

Examples:

• KNO₃: trioxonitrate(1-) of potassium
• CaSO₄: tetraoxosulfate(4+) of calcium
• NaClO: monoxochlorate(1-) of sodium
• Ca(ClO)₂: dioxochlorate(1-) of calcium
• Fe₂(SO₄)₃: tris(tetraoxosulfate)(2-) of iron(2+)
• CuNO₃: trioxonitrate(1-) of copper

Common oxosalts

• CaCO₃ (calcium carbonate): main component of limestone and marble.
• CaSO₄ (calcium sulfate): gypsum, used in plasters and construction.
• KNO₃ (potassium nitrate): used in fertilizers and food preservation.
• KMnO₄ (potassium permanganate): oxidizing agent and disinfectant.
• NaClO (sodium hypochlorite): common bleach and disinfectant.