1. Select the categories that you want to study. 2. Click Scratch Cat or press space. 3. Write your answer. 4. If you give the wrong answer, click Scratch Cat or press space to continue. 5. Repeat as much as you wish. This doesn't tell you about the properties of polyatomic ions or anything interesting like that. The point of this project is to try to memorise the common ones well enough that you can do your chemistry homework. Subscript numbers: ₀₁₂₃₄₅₆₇₈₉
