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Determine if the metal ion has a fixed charge or variable charge.

1. Read the name of the compound.

gold(I) nitrate

2. Determine if the metal ion has a fixed charge or variable charge.

gold = Group IB = variable charge = 1+ or 3+

3. Write the first chemical symbol based on the cation in the compound, including the charge. The name tells us it is gold(I) meaning it carries a 1+ charge.

gold(I) = Au+

4. Write the second chemical symbol based on the anion in the compound, including the charge.

nitrate ion = NO3 – 18 ©Hands-On Labs, Inc.

Experiment Naming Ionic and Molecular Compounds

5. Balance the charges to determine the correct number of atoms of each element to write the formula for a neutral compound.

6. Write the formula of the molecular compound.

gold(I) nitrate = AuNO3

Naming Acids

Simple covalent compounds that contain hydrogen often dissolve in water to produce acids. For example, HF in its gaseous state (g) is hydrogen fluoride, but HF in aqueous solution (aq) is hydrofluoric acid. This lesson focuses on binary acids and oxoacids. Binary acids are acids in which hydrogen bonds with a second nonmetallic element. An oxoacid is an acid containing oxygen, hydrogen, and a third element. An oxoacid contains at least one hydrogen atom bound to the oxygen. These acids dissociate in water by breaking the OH bond to form a H+ ion and an anion.

There are a unique set of rules for naming both binary and oxoacids. The systematic names for binary acids include the prefix “hydro-” (indicating the water the acid is dissolved in) and the root of the second element’s name (the non-metal). The suffix of the anion changes from “-ide” to “-ic,” followed by the word “acid.” For example:

water + H+ + F- = HF(aq) = hydrofluoric acid

Note: Acids containing sulfur use the full name “sulfur” instead of the root of the name. For example, H2S(aq) is called hydrosulfuric acid NOT hydrosulfic acid.

Oxoacids are named based on the nonmetal from which they are derived. The prefix “hydro-” is not used, and the suffix “-ate” is changed to “-ic,” and the suffix “-ite” is changed to “-ous.” For example, HNO3 (contains the nitrate ion) is named nitric acid. The prefixes used for lowest and highest oxidation states are also used in the naming of oxoacids. For example, HClO (contains the hypochlorite ion) is named hypochlorous acid. See Table 3 for examples of formulas and names for strong acids that may be encountered.