1. 1 Nomenclature Chapter 5

2. 2 5.1Naming Compounds Many compounds have common names: Ex:H 2 O = water NH 3 = ammonia CH 4 = methane There must be system for naming (nomenclature) the thousands of known chemical compounds. Compounds named in this chapter:  Binary compounds -- those composed of two elements: Metal with a nonmetal (ionic) Two nonmetals (nonionic)  Polyatomic compounds -- composed of a metal and a PA anion, or two PA ions.  Acids -- H + and an anion.

3. 3 5.2Naming Compounds that Contain a Metal and a Nonmetal Binary ionic compounds contain a metal cation and a nonmetal anion. Rules for naming:  Name the metal cation first, then name the nonmetal anion.  The metal cation name is the metal name.  The nonmetal anion name uses the root of the element name and adding – ide suffix.  See table 5.1

4. 4  For metals that can form more than one type of cation -- such as transition metals, and Group 4A metals -- the cation name is the metal name followed by a Roman numeral in parentheses to indicate its charge.  See Table 5.2 The net charge on an ionic compound is always zero. Examples: text pg 126-127, 129

5. 5 5.3Naming Binary Compounds Containing only Nonmetals These compounds do not contain ions. Rules for naming:  Name the first element in formula using the full name of the element.  Name the second element in the formula as if it were an anion (root name plus –ide suffix).  Use a prefix in front of each name to indicate the number of atoms. (See Table 5.3)  Never use the prefix mono- on the first element.  Drop last “a” in the prefix if the name begins with vowel.

6. 6 Table 5-3 Examples: see pages 132 -133 octa-8 hepta-7 hexa-6 penta-5 tetra-4 tri-3 di-2 mono- (Not on first element) 1 PrefixSubscript

7. 7 5.4(Skip) 5.5 Naming Compounds that Contain Polyatomic Ions Polyatomic ions are charged entities composed of several atoms bound together. Must memorize name, formula and charge.  See list of PA ions given you, or Table 5.4  Oxyanions – polyatomic anions that contain a given element with different numbers of oxygen.

8. 8 Polyatomic compounds:  are ionic compounds because they contain ions bonded together.  are not binary compounds because they contain more than two elements.  Contain a metal combined with a polyatomic ion or can be composed of two polyatomic ions  Examples:

9. 9 Rules for naming:  Name metal cations as in binary ionic compounds. (Use Roman numerals when necessary.)  Use the name of the polyatomic ion part of the compound as written.  Put parentheses around polyatomic ions when more than one is present.  Examples:

10. 10 5.6 Naming Acids Acids are compounds that produce H + cations and an anion when dissolved in water. Rules for naming: see handout

11. 11 5.7Writing the Formulas from the Names For binary ionic compounds (metal and a nonmetal), polyatomic compounds, and acids:  Determine the ions present.  Determine the charges on the cation and anion.  Balance the charges to get the formula subscripts. For binary compounds composed of two nonmetals, use the prefixes to determine the formula subscripts.