Chemical Nomenclature

Here is an overview of the guidelines for naming and writing formulas for several types of compounds.

Some names and formulas for compounds can be constructed from general rules, but others must be memorized. The following list includes some commonly encountered names and formulas that must be memorized.

water - H₂O

ammonia - NH₃

methane - CH₄

ethane - C₂H₆

propane - C₃H₈

methanol - CH₃OH

ethanol - C₂H₅OH

2-propanol (isopropyl alcohol) - C₃H₇OH

The general procedure for naming other compounds consists of two steps:

Step #1: Decide what type of compound the name or formula represents.

Step #2: Apply the rules for writing the name or formula for that type of compound.

The following summarizes the distinguishing features of different kinds of formulas and names.

Binary Covalent Compounds

General Formula  -  A_aB_b   -  For example, N₂O₅ or CO₂  

General Name - (prefix unless mono)(name of first element in formula) (prefix)(root of second element)ide - For example, dinitrogen pentoxide or carbon dioxide

Binary Ionic Compounds

General Formula - M_aA_b   -  F or example, NaCl or FeCl₃

General Name - (name of metal) (root of nonmetal)ide or (name of metal)(Roman #) (root of nonmetal)ide   -  For example, sodium chloride or iron(III) chloride

Ionic Compounds with Polyatomic Ion(s)

General Formula - M_aX_b or (NH₄)_aX_b   X = recognized formula of polyatomic ion   -  For example, Li₂HPO₄ or CuSO₄ or NH₄Cl or (NH₄)₂SO₄

General Name - (name of metal) (name of polyatomic ion) or (name of metal)(Roman #) (name of polyatomic ion) or ammonium (root of nonmetal)ide or ammonium (name of polyatomic ion) - For example, lithium hydrogen phosphate or copper(II) sulfate or ammonium chloride or ammonium sulfate

Binary Acids

General Formula - HX(aq)   -  For example, HCl(aq)

General Name - hydro(root)ic acid   -  For example, hydrochloric acid

Oxyacids

General Formula - H_aX_bO_c   -  For example, HNO₃ or H₂SO₄ or H₃PO₄

General Name - (root)ic acid   -  For example, nitric acid or sulfuric acid or phosphoric acid

The following links take you to pages that have more information about writing names and formulas for compounds.

Binary Covalent Nomenclature

Ionic Nomenclature

Cation Names and Formulas

Anion Names and Formulas

Acid Nomenclature