The IUPAC process for naming an oxyanion is defined by how much oxygen is bound to the central atom compared to the amount of oxygen that could be bound. We add a prefix and suffix to the root of the element name to indicate this.

Table 1: Table showing the relevant prefixes, suffixes for oxyanion and oxyacid naming.

Table for oxyanion and oxyacid naming. A table with five columns labelled from left to right as: Oxidation State, Least Oxygen, Less Oxygen, More Oxygen and Most Oxygen. The table shows that oxyanions with the least oxygen are given a hypo prefix and -ite suffix. Oxyanions with less oxygen are given a -ite suffix only and with more oxygen an -ate suffix only. Oxyanions with the most oxygen are given a per- prefix and an -ate suffix. Finally, the -ite ending oxyanion columns are combined to show the collective oxyacid suffix is -ous. The -ate ending columns are combined to show the collective oxyacid suffix is -ic.

For example, the chlorine oxyanion (ClO4-) cannot have more oxygen bound to the central atom. It is, therefore, in the final column of Table 1 and so we take the chlor- root and add the prefix, per, and the suffix, -ate.

Hence, ClO4- is called perchlorate.