Article — Chemical Name Lookup (Formula ↔ Name)
Chemical Name Lookup Tool
Chemical names follow systematic rules set by IUPAC. NaCl is sodium chloride. H₂SO₄ is sulfuric acid. CO₂ is carbon dioxide. The lookup tool above converts formula to name and back for about 65 common compounds — useful for homework, lab orders, and decoding old recipes.
What chemical nomenclature is
Nomenclature is the set of rules for naming compounds. Without it, chemists would each invent their own labels and no two laboratories could communicate. Before 1892, that was nearly the situation — French, German, and English chemists used different names for the same substances, and the literature was a maze of synonyms.
The International Union of Pure and Applied Chemistry (IUPAC) emerged from that chaos. The first internationally standardized naming scheme (the Geneva Nomenclature) appeared in 1892, predating IUPAC, which was founded in 1919; the current rules were updated comprehensively in 2013. Modern chemistry uses the IUPAC system across all subfields, with retained common names where tradition is too entrenched to change.
PubChem, the National Institutes of Health chemical database, lists over 110 million distinct compounds. About 2% have a widely-used common name; the rest are known only by their IUPAC systematic names. Without systematic nomenclature, modern chemistry would not function.
IUPAC versus common chemical names
IUPAC names describe the structure of a compound directly. "Dihydrogen monoxide" tells you that the molecule has two hydrogen atoms and one oxygen. "2,3-dihydroxypropanal" tells you the carbon chain length, the positions of the hydroxyl groups, and the aldehyde end.
Common names are historical leftovers. "Water" predates atomic theory by millennia. "Aspirin" was Bayer's brand name. "Aqua fortis" is the Latin for "strong water," an alchemical term for nitric acid still used in colloquial chemistry. Some common names are retained in IUPAC literature (water, ammonia, methane); others have been phased out (azote for nitrogen, marsh gas for methane).
Pharmaceutical naming follows a three-layer system. Each drug has an IUPAC name (precise, often unwieldy), an International Nonproprietary Name (INN, used in scientific writing — ibuprofen, acetaminophen), and one or more trade names (Advil, Tylenol). Doctors prescribe in INN; pharmacists dispense by trade or generic; chemists discuss in IUPAC.
Water H₂OSalt NaClBaking soda NaHCO₃Vinegar CH₃COOHBleach NaClOLye NaOHRust Fe₂O₃Naming ionic compounds
Ionic compounds form when a metal donates electrons to a nonmetal. The name is built by combining the cation (metal) name with the anion (nonmetal) name in -ide form. Sodium (Na) + chlorine (Cl) becomes sodium chloride. Calcium (Ca) + oxygen (O) becomes calcium oxide. Aluminum (Al) + fluorine (F) becomes aluminum fluoride.
Two complications. First, polyatomic anions keep their own names: NO₃⁻ is nitrate, SO₄²⁻ is sulfate, CO₃²⁻ is carbonate. So Na₂SO₄ is sodium sulfate, not sodium oxide-with-sulfur. Second, metals with multiple oxidation states get Roman numerals: Fe²⁺ is iron(II), Fe³⁺ is iron(III). FeCl₂ is iron(II) chloride; FeCl₃ is iron(III) chloride.
Naming covalent compounds
Two nonmetals form covalent compounds, named with Greek numerical prefixes. CO is carbon monoxide; CO₂ is carbon dioxide; N₂O₄ is dinitrogen tetroxide; P₂O₅ is diphosphorus pentoxide. The prefix tells you how many atoms of each element.
Two quirks. First, the mono- prefix is dropped from the first element: CO is "carbon monoxide," not "monocarbon monoxide." Second, vowel elision: penta + oxide becomes pentoxide (drop the trailing 'a' before a vowel). N₂O₅ is dinitrogen pentoxide, not pentaoxide.
The order of elements follows electronegativity: the less electronegative element comes first. Carbon (lower) before oxygen (higher), so CO and CO₂; nitrogen before oxygen, so N₂O and NO; sulfur before oxygen, so SO₂ and SO₃. Hydrogen sits between carbon and oxygen, so HCl, but H₂O has hydrogen first while OF₂ has fluorine last.
Greek prefixes in order: mono, di, tri, tetra, penta, hexa, hepta, octa, nona, deca. Numbers higher than 10 are rare in simple compounds; complex organic molecules use a different system entirely (IUPAC organic nomenclature).
Naming acids and bases
Acids fall into two groups. Binary acids (hydrogen + one nonmetal) take the form "hydro-X-ic acid" — HCl is hydrochloric acid, HBr is hydrobromic acid, HF is hydrofluoric acid. Oxyacids (hydrogen + polyatomic anion containing oxygen) follow the anion ending: -ate becomes -ic (H₂SO₄ → sulfate → sulfuric acid), -ite becomes -ous (H₂SO₃ → sulfite → sulfurous acid).
Bases are simpler. Metal hydroxides are named like ionic compounds: NaOH is sodium hydroxide, KOH is potassium hydroxide, Ca(OH)₂ is calcium hydroxide. Ammonia (NH₃) is a base in solution but follows its own retained common name.
Everyday chemicals and their formulas
Five household chemicals account for most kitchen and cleaning use. Sodium chloride (NaCl) is table salt. Sodium bicarbonate (NaHCO₃) is baking soda. Acetic acid (CH₃COOH) at 5% in water is vinegar. Sodium hypochlorite (NaClO) is laundry bleach. Sodium hydroxide (NaOH) is drain cleaner and oven cleaner. Knowing the chemical name lets you read safety data sheets confidently and avoid mixing reactive substances by accident.
Old-fashioned trade names persist in literature and craft instructions: oil of vitriol (H₂SO₄), aqua regia (HNO₃ + HCl), aqua fortis (HNO₃), spirit of salt (HCl), saltpeter (KNO₃), Glauber's salt (Na₂SO₄·10H₂O). When historical recipes call for these, the chemical-name lookup translates them to modern formulas.
Common chemical naming mistakes
Three errors recur in homework and laboratory documentation.
S²⁻ is sulfide (no oxygen). SO₄²⁻ is sulfate (with oxygen). Sulfur(II) compounds end in -ide; sulfur(VI) compounds with oxygen end in -ate. Calling Na₂S sodium sulfate (it is sodium sulfide) or Na₂SO₄ sodium sulfide (it is sodium sulfate) is the most common naming mistake.
Second: forgetting the Roman numeral on multivalent metals. "Iron chloride" is ambiguous. Is it FeCl₂ or FeCl₃? Always specify: iron(II) chloride or iron(III) chloride. Third: applying the wrong prefix to ionic compounds. CaCl₂ is calcium chloride, not calcium dichloride — prefixes are used only for covalent compounds. The charge balance (Ca²⁺ + 2 Cl⁻) already determines the formula.