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Nomenclature. Rules for naming compounds. Alkali & alkaline earth metals. For metals of Groups 1 & 2, write the metal’s name as it appears on the periodic table Change the ending of the nonmetal to “- ide ” Carbide Nitride, phosphide Oxide, sulfide Fluoride.
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Nomenclature Rules for naming compounds
Alkali & alkaline earth metals • For metals of Groups 1 & 2, write the metal’s name as it appears on the periodic table • Change the ending of the nonmetal to “-ide” • Carbide • Nitride, phosphide • Oxide, sulfide • Fluoride
Transition metals’ compoundsStock Method • When metal has more than one oxidation #, one designates the metal’s charge with a Roman numeral in parentheses behind the metal’s name • Copper (I) chloride = CuCl • Copper (II) chloride = CuCl2 • The nonmetal’s ending is changed to “-ide”
Determining metals’ charges • One examines the total charge of the anion • Using the octet rule, find # of electrons needed for nonmetal to achieve noble gas’ stable outer 8 e- • Group 15 = -3; Group 16 = -2; Group 17 = -1 • Multiply anion’s negative charge by its # subscript • Fe2O3 : Oxygen has charge of -2. O3 = (3)(-2) = -6 total • One balances this negative charge with the transition metal’s positive charge • O3= -6 Fe2= +6; +6/ 2 Fe = +3 per Fe • Iron (III) chloride
Exceptions in the d block • Zinc [Zn] always has oxidation # of 2+ • Cadmium [Cd] always has oxidation # of 2+ • Silver [Ag] always has oxidation # of 1+ • These NEVER use a Roman Numeral designator when naming their compounds • AgCl = silver chloride • ZnCl2 = zinc chloride • CdCl2 = cadmium chloride
Two Nonmetals • Because nonmetals can share their electrons in numerous ways, one designates their subscripts in a chemical formula with prefixes 1 = mono- 2 = di- 3 = tri- 4 = tetra- 5 = penta- 6 = hexa- 7 = hepta- 8 = octa- 9 = nona- 10 = deca- See Chemistry text, page 228
Examples of 2 Nonmetals • CCl4 = carbon tetrachloride • NO = nitrogen monoxide • N2O5 = dinitrogenpentoxide • CO2 = carbon dioxide • P4O10 = tetraphosphorusdecoxide • P2S3 = diphosphorustrisulfide NOTE: 1] Never start name with “mono-” 2] Drop “a/o” on prefix if double vowels sound bad
Binary Molecular Compounds • Covalent Network compounds may also use system of prefixes • Si3N4 = trisilicontetranitride • Metals right of the d block may also use Stock method (Roman numerals) OR prefixes • PbO2 = lead (IV) oxide OR lead dioxide • Transition metals may also use the system of prefixes in their nomenclature • Mo2O3 = molybdenum (III) oxide = dimolybdenum trioxide