IUPAC chemical nomenclature is the international standard for naming chemical compounds. This reference tool lets you search by chemical formula OR by compound name to find systematic IUPAC names, common names, compound types, and the naming rules applied. Covers ionic compounds, covalent molecules, acids, organic basics, and polyatomic ions.
IUPAC Naming Rules Reference
1. Ionic Compounds (metal + nonmetal)
Rule: Cation name (unchanged) + anion root + -ide
Examples: NaCl = sodium chloride, MgO = magnesium oxide, AlCl₃ = aluminum chloride
Transition metals with multiple charges use Roman numerals (Stock system): FeCl₂ = iron(II) chloride (Fe²⁺), FeCl₃ = iron(III) chloride (Fe³⁺)
Polyatomic anions keep their own names: Na₂SO₄ = sodium sulfate, KNO₃ = potassium nitrate
2. Covalent (Molecular) Compounds
Rule: Greek prefix + element 1 name + Greek prefix + element 2 root + -ide
Prefixes: mono- (1), di- (2), tri- (3), tetra- (4), penta- (5), hexa- (6), hepta- (7), octa- (8)
The first element omits "mono-" unless needed for clarity. If the prefix ends in a vowel and the element name starts with a vowel, the last vowel of the prefix is usually dropped.
Examples: CO₂ = carbon dioxide, N₂O₄ = dinitrogen tetroxide, SF₆ = sulfur hexafluoride, PCl₅ = phosphorus pentachloride
3. Acids
Binary acids (H + nonmetal, aqueous): hydro- + nonmetal root + -ic acid
Examples: HCl(aq) = hydrochloric acid, HBr(aq) = hydrobromic acid, H₂S(aq) = hydrosulfuric acid
Oxyacids (H + polyatomic ion with oxygen):
- -ate ion → -ic acid: H₂SO₄ (from sulfate) = sulfuric acid
- -ite ion → -ous acid: H₂SO₃ (from sulfite) = sulfurous acid
Examples: HNO₃ = nitric acid, H₃PO₄ = phosphoric acid, HClO₄ = perchloric acid
4. Organic Compound Basics
Chain length prefixes: meth- (1C), eth- (2C), prop- (3C), but- (4C), pent- (5C), hex- (6C), hept- (7C), oct- (8C)
Functional group suffixes:
- -ane: alkane (all single bonds) — CH₄ methane, C₂H₆ ethane
- -ene: alkene (one C=C double bond) — C₂H₄ ethene (ethylene)
- -yne: alkyne (one C≡C triple bond) — C₂H₂ ethyne (acetylene)
- -ol: alcohol (–OH) — CH₃OH methanol
- -al: aldehyde (–CHO) — HCHO methanal (formaldehyde)
- -oic acid: carboxylic acid (–COOH) — CH₃COOH ethanoic acid (acetic acid)
How to Use the Chemical Naming Tool
This tool provides bidirectional lookup for over 100 common compounds: search by formula to find the name, or search by name to find the formula. It covers the four main compound categories tested in general chemistry courses.
Searching by Formula
Type the chemical formula exactly as written: NaCl, H2SO4, CO2. The search is case-insensitive and handles common formatting variations. For polyatomic compounds, include subscripts directly in text form (SO4, NO3). Click any result card to see the full compound details including the naming rule applied.
Searching by Name
Type the IUPAC name or common name: "sodium chloride", "sulfuric acid", "methane". Partial matches work — typing "carbon" finds carbon dioxide, carbon monoxide, and carbonate compounds. The results show the formula in proper chemical notation with subscripts.
Example: Naming Iron(III) Oxide
Search for "Fe2O3" or "iron oxide". The result shows: IUPAC name = iron(III) oxide, type = ionic compound, naming rule = Stock system (transition metal with Roman numeral indicating +3 oxidation state on iron). The formula Fe₂O₃ requires Fe³⁺ because 2 × (+3) + 3 × (-2) = 0 (charge balance).
Filtering by Type
Use the category pills to filter by compound type. Ionic compounds have a metal cation and nonmetal anion. Covalent compounds have two nonmetals sharing electrons. Acids donate H⁺ in solution. Organic compounds are carbon-based. Polyatomic ions are charged multi-atom groups used to build ionic compounds.
FAQ
What is IUPAC nomenclature?
IUPAC (International Union of Pure and Applied Chemistry) nomenclature is the official system for naming chemical compounds. It provides unambiguous, systematic names so that any chemist worldwide can identify a compound from its name. For example, NaCl has the IUPAC name 'sodium chloride' and H2SO4 is 'sulfuric acid.'
How are ionic compounds named?
Ionic compounds are named by stating the cation (metal) name first, then the anion (nonmetal) name with the suffix '-ide'. For example, NaCl = sodium chloride, CaO = calcium oxide. Transition metals with multiple charges use Roman numerals: FeCl₂ = iron(II) chloride, FeCl₃ = iron(III) chloride.
How are covalent (molecular) compounds named?
Covalent compounds use Greek number prefixes for each element: mono- (1), di- (2), tri- (3), tetra- (4), penta- (5), hexa- (6), hepta- (7), octa- (8). The first element omits 'mono-'. Examples: CO₂ = carbon dioxide, N₂O₄ = dinitrogen tetroxide, PCl₅ = phosphorus pentachloride.
How are acids named?
Binary acids (H + nonmetal) use 'hydro-' prefix + nonmetal root + '-ic acid': HCl = hydrochloric acid, HBr = hydrobromic acid. Oxyacids use the polyatomic ion root: H₂SO₄ = sulfuric acid (from sulfate), HNO₃ = nitric acid (from nitrate), H₃PO₄ = phosphoric acid (from phosphate).
What are polyatomic ions?
Polyatomic ions are groups of atoms that carry a net charge: sulfate (SO₄²⁻), nitrate (NO₃⁻), phosphate (PO₄³⁻), carbonate (CO₃²⁻), hydroxide (OH⁻), ammonium (NH₄⁺). Their names don't follow the -ide rule — they have specific names that must be memorized. This tool lists all common polyatomic ions with their charges and formulas.
How are organic compounds named?
Simple organic compounds use the IUPAC prefix system for carbon chain length: meth- (1C), eth- (2C), prop- (3C), but- (4C), pent- (5C), hex- (6C). The suffix indicates the functional group: -ane (alkane, single bonds), -ene (alkene, double bond), -ol (alcohol, -OH group), -al (aldehyde), -oic acid (carboxylic acid).
Is this chemical naming tool free?
Yes, completely free. No account or signup required. All data is built into the tool and runs locally in your browser.