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Inorganic nomenclature is a systematic way of naming inorganic compounds.
Positively charged ions are called cations and negatively charged ions are called anions. The cation is always named first. Ions can be metals or polyatomic ions. Therefore the name of the metal or positive polyatomic ion is followed by the name of the non-metal or negative polyatomic ion. The positive ion retains its element name whereas for a single non-metal anion the ending is changed to -ide.
Example: sodium chloride, potassium oxide, or calcium carbonate.
When the metal has more than one possible ionic charge or oxidation number the name becomes ambiguous. In these cases the oxidation number of the metal ion is represented by a Roman numeral in parentheses immediately following the metal ion name. For example in uranium(VI) fluoride the oxidation number of uranium is 6. However in this case the non IUPAC name uranium hexafluoride is often used. Another example is the iron oxides. FeO is iron(II) oxide and Fe2O3 is iron(III) oxide.
For naming metal complexes see the page on complex (chemistry).
An older system used prefixes and suffixes to indicate the oxidation number, according to the following scheme:
|Oxidation state||Cations and acids||Anions|
|Lowest||hypo- -ous||hypo- -ite|
|Highest||per- -ic||per- -ate|
Thus the four oxyacids of chlorine are called hypochlorous acid (HOCl), chlorous acid (HOClO), chloric acid (HOClO2) and perchloric acid (HOClO3), and their respective conjugate bases are the hypochlorite, chlorite, chlorate and perchlorate ions. This system has partially fallen out of use, but survives in the common names of many chemical compounds: the modern literature contains few references to "ferric chloride" (instead calling it "iron(III) chloride"), but names like "potassium permanganate" (instead of "potassium manganate(VII)") and "sulfuric acid" abound.
List of common ion names
- NH4+ AMMONIUM
- H3O+ HYDRONIUM
- NO3- NITRATE
- NO2- NITRITE
- ClO- HYPOCHLORITE
- ClO2- CHLORITE
- ClO3- CHLORATE
- ClO4- PERCHLORATE
- SO32- SULFITE
- SO42- SULFATE
- HSO3- BISULFITE (or HYDROGEN SULFITE)
- HCO3- BICARBONATE (or HYDROGEN CARBONATE)
- CO32- CARBONATE
- PO43- PHOSPHATE
- HPO42- HYDROGEN PHOSPHATE
- H2PO4- DIHYDROGEN PHOSPHATE
- CrO42- CHROMATE
- Cr2O72- DICHROMATE
- BO33- ORTHOBORATE
- AsO43- ARSENATE
- C2O42- OXALATE
- CN- CYANIDE
- MnO4- PERMANGANATE
- Cl- CHLORIDE
- S2- SULFIDE
- P3- PHOSPHIDE
IUPAC nomenclature (covers only organics at present)
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