Nomenclature
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Nomenclature

For the purposes of naming acids and bases we will put these chemicals into three categories: binary acids, ternary acids (sometimes called oxy-acids), and bases.

Binary Acids

Binary acids contain hydrogen and one other nonmetallic element. Their names follow the pattern of "hydroelementic acid" where element is replaced by the root of the name of the element. These acids contain no oxygen. Here are some examples.

HF hydrofluoric acid
H2S hydrosulfuric acid
HBr hydrobromic acid

Note that the names of binary acids do not indicate how many hydrogen atoms are in the formula. That is determined by the valence of the other element.

Ternary Acids or Oxy-acids

Ternary acids contain hydrogen and oxygen and one other (usually) nonmetallic element. The names of the most common ones follow the pattern of "elementic acid" where element is replaced by the root of the name of the other element. Note that these acids contain both hydrogen and oxygen but their names make no reference to either hydrogen or oxygen. Here are some examples.

H2SO4 sulfuric acid
HClO3 chloric acid
H2CO3 carbonic acid
H2CrO4 chromic acid

Note that the names of ternary acids do not indicate how many hydrogen atoms are in the formula, nor do they indicate how many oxygen atoms are in the formula. That needs to be learned by memorization or repetition. However, if you remember the formulas of the common polyatomic ions, these acids contain the same number of oxygen atoms as those, and the number of hydrogen atoms matches the negative charge on the ions. We will look at that relationship more fully later in this lesson and also in a later lesson.

There are also ternary acids for which the names follow the pattern "elementous acid." The formulas of these acids contain one less oxygen than the "elementic acids." Here are two examples.

H2SO3 sulfurous acid
HClO2 chlorous acid

Bases

Bases are simply named as ionic compounds containing the hydroxide ion. Here are some examples.

NaOH sodium hydroxide
Ca(OH)2 calcium hydroxide
Fe(OH)3 iron(III) hydroxide
ferric hydroxide
NH4OH ammonium hydroxide

 

 

Practice

We will deal more with nomenclature of acids, bases, salts and polyatomic ions in a later lesson. But for now, for practice, try your hand at naming the acids and bases listed below (and shown in exercise 6 in your workbook). To keep it simple, none of the acids has an -ous ending in its name.

HCl HNO3 H2SO4
H3PO4 NaOH KOH
Mg(OH)2 Al(OH)3 NH4OH

 

Answers

HCl hydrochloric acid
HNO3 nitric acid
H2SO4 sulfuric acid
H3PO4 phosphoric acid
NaOH sodium hydroxide
KOH potassium hydroxide
Mg(OH)2 magnesium hydroxide
Al(OH)3 aluminum hydroxide
NH4OH ammonium hydroxide

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