C-H-E-M-I-C-A-L-naming-of-compounds.pdf

CHEMICAL FORMULAS AND NAMES MELC: Name compounds given their formula and write formula given the name of the c o m p o u n d STEM_GC11AMIc-e-23  Just as letters of the alphabet to form words, chemical symbols combine to form chemical formulas of compounds. Different arrays of inorganic compoun...

CHEMICAL FORMULAS AND NAMES MELC: Name compounds given their formula and write formula given the name of the c o m p o u n d STEM_GC11AMIc-e-23  Just as letters of the alphabet to form words, chemical symbols combine to form chemical formulas of compounds. Different arrays of inorganic compounds are named according to different systems of nomenclature. We will now try to read and write chemical formulas of simple compounds. Naming and writing formulas for compounds are very important skills. COMMON AND SYSTEMATIC NAMES OF COMPOUNDS The systematic names of compounds were established according to the rules of International Union of Pure and Applied Chemistry ( IUPAC ). This set of rules called nomenclature is used to systematically name over 10 million compounds known today. However, these rules were not recognized long after many chemical compounds were known by many different names, or their common names. The common names ( as composed to the systematic names) of many compounds are still used today.  Formula Systematic Name Common Name NaHCO3 Sodium bicarbonate Baking powder CaOCl2 Calcium Oxychloride Bleaching powder CaCO3 Calcium Carbonate Chalk (Marble) NaOH Sodium Hydroxide Caustic Soda H2O2 Hydrogen Peroxide Agua Oxygenada MgSO4 · 7H2O Magnesium sulfate heptahydrate Epsom salt CCl2F2 Dichlorodifluoromethane Freon CaSO4 · 2H2O Calcium sulfate dihydrate gypsum Formula Systematic Name Common Name CH3COC2H5 Ethyl methyl ketone acetone FeS2 Iron sulfide Iron pyrite ( fool’s gold) SiO2 Silicon dioxide Quartz C12H22O11 Sucrose Table sugar  A chemical formula is a short hand representation of compounds using symbols and oxidation numbers. The simple way to learn to write chemical formulas is to use the crisscross method. 1. Write the symbol for each element (or formula for ions.). Calcium Chlorine Ca +2 Cl –1 CaCl2  A binary compound is consist of two different kinds of elements and can further classified into binary ionic compounds and binary covalent compounds. Binary ionic compounds contain two ions, one positively charged (cation) and one negatively charged (anion), that react to form a compound. One must remember that cation formers are usually metallic elements and anion formers are usually nonmetallic elements. Naming Binary Ionic Compounds Ionic compounds may be composed of a metal that has a fixed oxidation number or a variable oxidation number and a nonmetal. Metal with Fixed oxidation Numbers Cations or all metals found in groups 1A, 2A, and 3A (Boron and Aluminum only) have a fixed oxidation numbers. This means that they have only one oxidation number  Metals that belong to the transition element can form more than one ion( variable oxidation number), each with a specific charge. In naming compounds made from these elements we can use either of the two systems. The first system is called the stock system. This system indicates the metal’s ionic charge by writing it in Roman numerals within parentheses. The second is classical system. This uses the suffixes –ous and –ic with the Latin names of the metals to indicate the lower and higher oxidation number ION STOCK SYSTEM CLASSICAL SYSTEM Co+3 Cobalt (III) Cobaltic Co+2 Cobalt (II) Cobaltous Fe+3 Iron (III) Ferric Fe+2 Iron (II) Ferrous ION STOCK SYSTEM CLASSICAL SYSTEM Cu+2 Copper (II) Cupric Cu+ Copper (I) Cuprous Hg+2 Mercury (II) Mercuric Hg+ Mercury (I) Mercurous Au+3 Gold (III) Auric Au+ Gold (I) Aurous ION STOCK SYSTEM CLASSICAL SYSTEM Sn+4 Tin (IV) Stannic Sn+2 Tin (II) Stannous Pb+4 Lead (IV) Plumbic Pb+2 Lead (II) Plumbous  Name this compound = Fe2O3 1. Determine the oxidation number of the cation. Crisscross the subscripts back to the exponent. 2. Name the cation. Iron ( III ) or Ferric 3. Name the anion changing the suffix to –ide = Oxide  Name the classical and stock name of the following compounds. 1. PbO 4. SnO2 2. PbO2 5. FeCl3 3. SnO 6. CuF2  Generally, a chemical formula is named first and is immediately followed by the second element. It is preceded by the prefix indicating the number of subscript of the second nonmetal with its root and suffix –ide. Greek prefixes are used to indicate the subscript. The first elements has a prefix only when the subscript is more than one. The second element always has a prefix..  Greek prefix Number Greek prefix Number mono 1 hexa 6 di 2 hepta 7 tri 3 octa 8 tetra 4 nona 9 penta 5 deca 10  Example 1 Write the name for P2O3. Diphosphorus trioxide  Example 2. Write the name for CO. Carbon monoxide Note that “monoxide” is written rather than “oxide” when there is one atom of the second element involved. When one element of the first atom is involved no “mono” is used.  Example 3. Write the name for N3O5. Trinitrogen pentoxide  Example 4 Write the name for OF2. Oxygen difluoride Example 5. Silicon trioxide SiO3