Naming polyatomic ionic compounds is the tricky one, and there are several rules depending on the different ions involved. When a hydrogen ion is involved, the compound starts with either hydrogen or dihydrogen, depending on if there are one or two ions involved. If oxygen is one of the anions, then it is an oxyanion. If there are only two forms of the oxyanion, it gets the suffix -ite for the smaller ion and -ate for the larger ion. If there are four versions of the oxyanion, the smallest gets the prefix hypo- and the suffix -ite. The next smallest gets just the suffix -ite. The third one gets the suffix -ate. The fourth and largest oxyanion gets the prefix per- and the suffix -ate.