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

For 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

 

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