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Jump to one of the following inorganic nomenclature parts:   Choose One Introduction to Inorganic Nomenclature Part 1- Molecular Compounds Part 2- Monatomic Ions Part 3- The Stock System Part 4- Polyatomic Ions Part 5- Ionic Compounds Part 6- Binary Acids and Oxoacids Part 7- Quizzes

Take an electron away from a sodium atom and you end up with a sodium ion, Na¹⁺. Add 3 electrons to a nitrogen atom and you end up with a nitride ion, N³⁺. These are examples of monatomic ions. Now we'll get into something a little more complex called polyatomic ions.

Polyatomic means "many atoms". For example, the acetate ion is C₂H₃O₂^1-. The ion's charge of 1+ belongs to the entire species and not just to one of the atoms in the polyatomic ion. The ion is made up of 2 or more different elements (carbon, hydrogen, and oxygen for acetate). You need to think of a polyatomic ion as a single entity. And while the the atoms of the polyatomic ions themselves are bound with covalent bonds, it is still an ion and will form ionic compound with the appropriate cations or anions.

This tutorial will not cover how the names were decided upon or how the charges for the polyatomic ions were decided upon. You will have access to the list of polyatomic ions included here. The purpose for doing that is mainly to minimize memorization. In this situation, I feel it's more important to understand how to use the ions when it comes to naming compounds. If you are a chemistry major or if you're going into pharmacy, you'll get a lot of exposure to the ions over time and you will become comfortable with a list much larger than the one covered here.

There is something you need to beware of, however. It's my experience that a number of students make a serious mistake in this section. Hey, since I don't require my classes to memorize the list and since you'll get the list on the exams, it's not as if you need to become comfortable with the polyatomic ions, right? Heck, they're on a piece of paper... what's so bleedin' hard about that?

BZZZT! But thank you for playing.

You need to become familiar with this list. Familiar enough so you can recognize the difference between the sulfide, S²⁺, sulfate, SO₄^2-, and sulfite, SO₃^2- ions. They are all three different ions and yet their names are close enough such that they can easily be mixed up. Especially if you don't do some practicing.

Hint

Get the table of polyatomic ions.

Now we're finally ready to learn how to put ions together to make compounds and how we name them.