Chemical Nomenclature 3 Systems of Naming Compounds

Binary Ionic Compounds Compounds formed from main group elements are determined by crossing the known charges or oxidation numbers to determine the number of each ion. Example: Mg 2+ P 3- Mg 3 P 2

Transition Metals: Traditional System Does not apply to ionic compounds formed from main group metals (Groups I and II) Name the metal first; use Latin names of metals. In binary compounds the nonmetal takes the suffix –ide. Some transition metals can form more than one ion The ion with the lower charge takes the suffix –ous The ion with the higher charge takes the suffix –ic.

Traditional system II ElementLower chgHigher Chg. CopperCuprous +1Cupric +2 IronFerrous +2Ferric +3 AntimonyStibnous +2Stibnic +4 LeadPlumbous +2Plumbic +4 NickelNickelous+1Nickelic+2

Traditional system III How can you tell which ion is present? Determine the charge on the nonmetal species, which is constant, and the charge on the metal which balances the negative charge on the nonmetal will reveal which ion is present. FeCl 2 Ferrous or Ferric? –Fe +2 + Cl - –Ferrous chloride –What will be the formula of Ferric chloride? –FeCl 3 The – charge on chloride does not change, only the charge on the + ion has changed. The formula for the compound is changed accordingly.

Traditional system IV Cu 2 O Cuprous or cupric oxide? Cuprous, Charge of +1 on the copper ion means 2 ions must neutralize –2 charge on oxide Formula for cupric oxide? CuO

Transition metals: Stock system Instead of Latin names and suffixes to indicate which ion is present, Roman numerals and modern names are used. Cu 2 O Copper (I) oxide CuO Copper (II) oxide Use the same system for any transition metal which forms more than one ion.

Comparison of Nomenclature systems FormulaTraditional system Stock system Fe 2 O 3 Ferric oxideIron (III) oxide Cu 3 P 2 Cupric phosphide Copper (II) phosphide

Prefix system Use the following prefixes to denote how many ions or atoms are present 1mono- 2di- 3tri- 4tetra- 5penta- 6hexa- 7hepta- 8octa- 9non- 10 deca- 12dodeca-

Prefix system Carbon monoxide CO Most often the mono- prefix is understood in the same way as a subscript of 1 is understood if there is no need to differentiate between them Carbon dioxide CO 2 Sulfur trioxide SO 3 All you have to do is count. Rarely used for ionic compounds; use with covalent compounds between nonmetals

Assignment Binary Compound Drill Sheet Prepare for first nomenclature quiz Tuesday