Resources

Learning to Name and Write Formulas:

- Determining the type of compound you are working with.

- Applying the rules for naming or formula writing for that type of compound.

- Practicing until it becomes second nature.

How to Memorize the Polyatomic Ions

In addition to monoatomic ions (Na⁺, Cl^-, Fe³⁺, N^3-) we have polyatomic ions. Polyatomic ions are made up of more than one element and have an overall charge. Examples are SO₄^2-, OH^-, and NH₄⁺.

Polyatomic ions are important in chemistry because they are found in many common chemical compounds. Because of this, it is helpful to memorize the most common of these ions. Some teachers do allow students to use a list of polyatomic ions for exams while others do not. However, memorizing the most common is recommended.

How do you name polyatomic ions?

Essentially you need to memorize or look up the polyatomic ions. There are some patterns in how they are named that can help in memorizing. Often a list of polyatomic ions is provided to students although many teachers require you memorize the most common ones.

Where does the charge come from?

Polyatomic ions get their charge by transferring electrons from another element. For example In NaNO₃ the Na loses an electron and the NO₃ gains the electron. Since then now have opposite ionic charges (the Na becomes Na⁺ and the NO₃ becomes NO₃^-) the form an ionic bond.