Naming Ionic Compounds
Name the metal then the non-metal with an -ide ending.
About this topic
Ionic compounds are named with the cation first, then the anion with its ending changed to -ide: sodium chloride, magnesium oxide. For metals with more than one possible charge, a Roman numeral shows the charge, as in iron(III) oxide for Fe2O3. Compounds with polyatomic ions keep the ion's name, such as calcium carbonate.
To write a formula from a name, work out each ion's charge and balance the totals. Calcium nitrate has Ca2+ and NO3-, so you need two nitrates: Ca(NO3)2. For the reverse, identify the ions and name them without prefixes, since the ratio is set by the charges. Group 1, group 2, aluminium, zinc and silver have fixed charges and need no numerals. Transition metals like copper, iron and lead usually need them. Older names use endings, ferrous and ferric, cuprous and cupric.
Examples: CuCl2 is copper(II) chloride because two Cl- balance Cu2+; K2S is potassium sulfide; and NH4Cl is ammonium chloride. Naming correctly matters for safety labels, medicine and trade.
A common error is using prefixes such as di- or tri- for ionic compounds (that is for covalent ones), forgetting the Roman numeral, or ending a polyatomic ion with -ide when it should be -ate or -ite. Remember that hydroxide and cyanide are exceptions that end in -ide.
Key ideas
- NaCl sodium chloride
- Roman numerals for variable charges
- Polyatomic ions keep their names
Quick check
Use cases: where Naming Ionic Compounds helps
- Homework: review the key idea behind Naming Ionic Compounds before you start a problem set.
- Exam revision: use the quick check to test whether you can recall Naming Ionic Compounds without notes.
- Visual learning: play with the interactive lab to see how Naming Ionic Compounds changes when you adjust its inputs.
- Teaching a friend: explain Naming Ionic Compounds in your own words, then compare your version with the key ideas.
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Frequently asked questions
What is Naming Ionic Compounds?
Name the metal then the non-metal with an -ide ending.
What will I learn in Naming Ionic Compounds?
NaCl sodium chloride. Roman numerals for variable charges. Polyatomic ions keep their names.
Is Naming Ionic Compounds part of Chemistry?
Yes. It is one of 150 Chemistry topics on LearnViz HighSchoolEdu, with 3 key ideas, a live animation and a quick check.
Does the Naming Ionic Compounds lab work on a phone or tablet?
Yes. The animation resizes to fit your screen and supports touch, so you can drag, tap and slide with your finger.
How should I study Naming Ionic Compounds?
Read the summary and key ideas first, play with the interactive lab to see the idea in motion, then answer the quick check. If you get a question wrong, go back to the key idea it tests.
Do I need an account, and is my progress saved?
No account is needed. Marking a topic as learned is saved in your own browser, so it stays on that device and is not sent to a server.