Chemistry Names: -ide, -ate, -ite, and Number Prefixes

Decode chemical compound names using systematic endings and Greek number prefixes.

Chemical names are designed to be decoded. In a simple compound of two elements, the second element takes the ending -ide: sodium chloride (sodium and chlorine), calcium oxide. When a group of atoms includes oxygen, -ate and -ite tell you how much: sulfate has more oxygen than sulfite, nitrate more than nitrite. Greek number prefixes count atoms in molecular compounds: mono- (1), di- (2), tri- (3), tetra- (4), penta- (5). Carbon monoxide has one oxygen; carbon dioxide has two. Poly- means many, as in polymer (meros, 'part'), a long chain of repeated units.

Iso- means equal, as in isotope (topos, 'place'), atoms of the same element, occupying the same place on the periodic table, with different numbers of neutrons. Worked example: 'dinitrogen tetroxide. ' Di- means two nitrogen atoms; tetr- means four oxygen atoms, so the formula is N2O4. The name is a recipe.

• 1-ide ends simple two-element compounds.
• 2-ate has more oxygen than -ite.
• 3Mono-, di-, tri-, tetra- count atoms; poly- means many.