Hypo- prefix

An anion derived from a ternary acid with an -ic ending is named by dropping the -ic acid and replacing it with -ate. An anion derived from an -ous acid is named by replacing the suffix -ous acid with -ite. The per- and hypo- prefixes are retained. 

One may think of the -ite ending as meaning one fewer oxygen atom. The per- and hypo- prefixes then mean one more oxygen atom and still one fewer oxygen atom, respectively. Other elements have similar sets of oxyanions, but not all have four different oxyanions. 

Finally, an oxyradical can have two less oxygen atoms than the base state. The oxyradical name will now have a hypo prefix and the suffix will be ite. An example would be aluminum hypophosphite. In the following example, calcium is combined with the oxyradical hypochlorite the resulting compound is calcium hypochlorite, a common swimming pool chlorinator. Calcium hypochlorite is an oxidizer and a fire risk when in contact with organic materials. 

When a nonmetal forms more than two oxoanions, the prefixes per- (largest number of oxygen atoms) and hypo- (fewest oxygen atoms) are used as well... 

The names of oxoacids are simply related to those of the corresponding oxoanions. The -ate suffix of the anion is replaced by -ic in the acid. In a similar way, the suffix -ite is replaced by the suffix -ous. The prefixes per- and hypo- found in the name of the anion are retained in... 

Some elements—particularly the halogens—form more than two kinds of oxoanions. The name of the oxoanion with the smallest number of oxygen atoms is formed by adding the prefix hypo- to the -ite form of the name, as in the hypochlorite ion, CIO-. The oxoanion with the most oxygen atoms is named with the prefix per- added to the -ate form of the name. An example is the perchlorate ion, C104-. The rules for naming polyatomic ions are summarized in Appendix 3A and common examples are listed in Table D.l. 

Oxyanions consist of an atom of an element plus some number of atoms of oxygen covalently bonded to it. The name of the anion is given by the name of the element with its ending changed to either -ate or -ite. In some cases, it is also necessary to add the prefix per- or hypo- to distinguish all the possible oxyanions from one another. For example, there are four oxyanions of chlorine, which are named as follows ... 

This rule does not change if the anion has a prefix per- or hypo- if the anion has such a prefix, so does the acid. If not, the acid does not either. 

One atom of tin and four atoma of oblorine form Stnimie olUoride. Sometimes, however, the same dements form with each other more than two compounds, In these cases the prefixes hypo and per are employed as marks of distinction but their use is very rarely requir. ... 

When there are more than two oxoanions in a series, the prefix hypo- (meaning "less than") is used for the ion with the fewest oxygens, and the prefix per- (meaning "more than") is used for the ion with the most oxygens. 

The complex oxy-anions are named in a somewhat systematic matter by using -ate for the most common or most stable and -ite for the ion containing less oxygen. The prefix per- is added to an -ate name to indicate even more oxygen, and the prefix hypo- is added to an -ite name to indicate a lower oxygen content than in the -ite ion. The system takes a bit of getting used to, but does work well. 

Oxoanions (also called oxyanions) contain one element in combination with oxygen. Many common polyatomic anions are oxoanions that end with the suffix -ate. If an element has two possible oxoanions, the one with the element at a lower oxidation state ends with -ite. This anion will also usually have less oxygen per atom. Additional oxoanions are named with the prefix hypo- if they have a lower oxidation number than the -ite form and the prefix per- if they have a higher oxidation number than the -ate form. 

There are special naming rules for acids that correspond with the suffix of their corresponding anion if hydrogen were removed from the acid. Anions ending with -ide correspond to acids with the prefix hydro- and the suffix -ic. Anions ending with -ate correspond to acids with no prefix that end with -ic. Oxoanions ending with -ite have associated acids with no prefix and the suffix -ous. The hypo- and per- prefixes are maintained. Some examples are shown in the following table ... 

The prefixes hypo- and per- remain as part of the acid name. For example, the acid of the perchlorate anion, CIO4", is perchloric acid, HCIO4. The acid of the hypochlorite anion, CIO", is hypochlorous acid, HCIO. 

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