When naming acids, there are several guidelines that must be followed. The rule for naming acids depends on whether the anion contains oxygen. If the anion does not contain oxygen, acid is named with prefix hydro- and suffix -ic to the root of element. If the anion does contain oxygen, the name is formed from root name of central element of anion or anion name, with a suffix of -ic or -ous. When anion name ends in -ate, the suffix -ic is used.