Chemistry 11 · Chemistry · Lesson 3.3
Naming ionic compounds and hydrates
- Level
- Grade 11
- Reading time
- 11 min reading
- Review
- Last reviewed 2026-09-03
- Standard
- Accuracy standard
- Errata
Abstract
Naming from a formula (Stock system) and naming hydrates.
How do you name ionic compounds?
Short answer
To name an ionic compound, name the cation (metal) first, then the anion (non-metal) with its ending changed to -ide, as in sodium chloride. Polyatomic ions keep their own names. When a metal forms more than one charge, a Roman numeral shows which one, as in iron(III) oxide. No prefixes are used for ionic compounds.
Concept preview
What you will be able to do
- 01Name simple ionic compounds from their formulas
- 02Use the un-criss-cross method to find a metal's charge
- 03Name hydrated ionic compounds
Naming is the reverse of formula-writing. If the first (metal) ion has only one possible charge, simply write the names of the two ions in order, dropping the word 'ion'. So is zinc chloride ( = zinc, = chloride) and is silver sulfate. You can assume the negative ion has its one usual charge from the table.
School Plan
Naming ionic compounds and hydrates
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Related topics
Frequently asked questions
- When do you use a Roman numeral in an ionic name?
- When the metal can have more than one charge (like iron or copper), the numeral shows which charge it has in that compound.
- Do ionic compounds use prefixes like "di" or "tri"?
- No. Prefixes are used only for molecular compounds; ionic names are set by the ion charges.