Nomenclature Reference
Interactive reference for inorganic chemical naming conventions. Review rules for ionic, covalent, and acid compounds, browse common polyatomic ions, and test your knowledge with practice problems.
Binary Ionic Compounds (Metal + Nonmetal)
General Rule:
Name the metal first (unchanged), then the nonmetal with an -ide suffix.
Variable-Charge Metals:
Use Roman numerals in parentheses to indicate the metal’s charge. Common examples: Fe (II, III), Cu (I, II), Pb (II, IV), Sn (II, IV), Co (II, III), Mn (II, IV, VII).
Common Nonmetal Suffixes:
Cl→ chloride
Br→ bromide
I→ iodide
F→ fluoride
O→ oxide
S→ sulfide
N→ nitride
P→ phosphide
Se→ selenide
Examples
| Formula | Name | Explanation |
|---|---|---|
| NaCl | Sodium chloride | Na⁺ + Cl⁻: metal + nonmetal, -ide suffix |
| CaBr₂ | Calcium bromide | Ca²⁺ + 2Br⁻: alkaline earth + halide |
| Al₂O₃ | Aluminum oxide | 2Al³⁺ + 3O²⁻: charges cross to subscripts |
| FeCl₂ | Iron(II) chloride | Fe²⁺ + 2Cl⁻: Roman numeral for variable-charge metal |
| FeCl₃ | Iron(III) chloride | Fe³⁺ + 3Cl⁻: same metal, different charge |
| CuO | Copper(II) oxide | Cu²⁺ + O²⁻: transition metal requires Roman numeral |
IUPAC nomenclature rules for inorganic chemistry. · Stock notation (Roman numerals) is used for transition metals with variable oxidation states. · Practice answers are case-insensitive.