Classify, name and connect inorganic substances
Classification turns many formulae into four manageable families: oxides, acids, bases and salts. Nomenclature identifies composition, while genetic links show how one class can be converted into another by chemical reactions.
Learning goals: recognize the four classes from formulae; use school-level IUPAC names and oxidation-state numerals; write neutral formulae; predict common reactions; build and justify transformation chains.
1. Four major classes
| Class | Recognition | Examples | Typical reaction |
|---|---|---|---|
| Oxide | binary compound with oxygen, usually O at −2 | CaO, CO2, Fe2O3 | basic oxide + acid; acidic oxide + base |
| Acid | ionizable H at the beginning and an acid residue | HCl, H2SO4, HNO3 | acid + base → salt + water |
| Base | metal or NH4 group with hydroxide OH | NaOH, Ca(OH)2, Cu(OH)2 | base + acid → salt + water |
| Salt | cation combined with an acid-residue anion | NaCl, K2SO4, CaCO3 | exchange reactions when a precipitate, gas or weak electrolyte forms |
2. Naming systematically
For an ionic compound, name the anion then the cation in the language's conventional order. If a metal has variable oxidation states, show the state with a Roman numeral: FeO is iron(II) oxide and Fe2O3 is iron(III) oxide. Hydroxides contain the word hydroxide. Common acids use established school names such as hydrochloric acid, sulfuric acid and nitric acid. Salts are named from their anion: chloride, sulfate, nitrate and carbonate.
A Roman numeral gives the oxidation state of the named element, not the number of atoms. In iron(III) oxide, III means Fe has oxidation state +3.