Ionic Compounds. And Acids

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1 CHAPTER 7 LANGUAGE OF CHEMISTRY CLASSIFICATION OF COMPOUNDS Inorganic compounds does not contain the element carbon, but there are exception to this rule, CO 2 (carbon dioxide), CO 3 2 (carbonate), and HCO 3 (hydrogen carbonate). There are five common classes of inorganic compounds: Binary ionic: These compounds contain one metal and one nonmetal, example, KCl, AlCl 3. Ternary Ionic: These compounds contain 3 elements with at least one metal, one nonmetal, example, KNO 3, Al(NO 3 ) 2 Binary Molecular: These compounds contain two elements that are both nonmetals, example, H 2 O, NH 3 Binary Acids: Aqueous solution of compound containing hydrogen and other nonmetal. Formulas of acids begin with H, example, HCl (aq), H 2 S (aq) Ternary Oxyacids: Aqueous solution of a compound containing H, a nonmetal, and oxygen, example, HNO 3(aq), H 2 SO 4(aq) Aqueous solution is produced when a compound dissolves in H 2 O. Chart showing different groups of Inorganic compound. Inorganic Compounds And Acids Ionic Compounds Aqueous Acids Binary Ionic Compound Ternary Ionic Compound Binary Molecular Compound Binary Acid Ternary Oxy Acids CLASSIFICATION OF IONS A positive ion is called CATION while a negative ion is called ANION. A single atom bearing positive or negative charge is called MONOATOMIC ION, example, Cl, Mg 2+. A group of atoms bound together and having overall positive or negative charge is called POLYATOMIC ION, example, SO 4 2, CO

2 MONOATOMIC IONS The names of most monoatomic cations are derived from parent metal; for example, the sodium ion, Na +. Cations having two possible ionic charges (transition metals) require further identification. The ionic charge may be indicated using either the Stock system or the Latin system. The stock system indicates the charge on the metal with Roman numerals in parenthesis. The Latin system attaches the suffix ous or ic to the Latin name of the element. Thus, Cu 2+ is named copper (II) ion according to stock system, and cupric ion using Latin system. The names of monoatomic anions are derived from parent nonmetal. A monoatomic anion is named using the nonmetal stem and attaching the suffix ide, example, Cl, chloride ion O 2, oxide ion. POLYATOMIC IONS Polyatomic anions generally contain one or more elements combined with oxygen Oxyanions. Their names end ate and ite, example, SO 2 4 sulfate ion SO 2 3 sulfite ion ( this group have one less oxygen than ate group) ClO 3 chlorate ion ClO 2 chlorite ion An exception group exists with suffix ide CN cyanide ion OH hydroxide ion NH + 4 ammonium ion CATION NH4+ COMMON POLYATOMIC IONS IUPAC NAME ammonium ion ANION IUPAC NAME ANION IUPAC NAME C 2 H 3 O 2 Acetate ion OH Hydroxide ion 2 CO 3 Carbonate ion ClO hypochlorite ion ClO 3 Chlorate ion NO 3 Nitrate ion ClO 2 Chlorite ion NO 2 Nitrite ion 2 CrO 4 Chromate ion ClO 4 Perchlorate ion CN Cyanide ion MnO 4 Permanganate ion 2

3 2 Cr 2 O 7 Dichromate ion 3 PO 4 HCO 3 Hydrogen carbonate ion 2 SO 4 sulfate ion HSO4 Hydrogen sulfate ion 2 SO 3 Sulfite ion Phosphate ion WRITING CHEMICAL FORMULAS An ionic compound is composed of positive and negative ions. A formula unit is the simplest representative particle in an ionic compound. A formula unit is neutral, therefore the total number of positive ions(from metals) is equal to the total number of negative ions ( from nonmetals) in both formula unit and ionic compound. Examples, Na + + Cl NaCl Ca Cl CaCl 2 Al Cl AlCl 3 Pb O 2 PbO 2 Formulas Containing Polyatomic Ions 2K SO 4 K 2 SO 4 NH SO 4 (NH 4 ) 2 SO 4 BINARY IONIC COMPOUND Ionic compounds have overall charge of zero, even though it contains charged ions from the metal(positive ion) and nonmetals(negative ions). Fe O X this gives, Fe 2 O Co N X this gives, CoN 3 3 When writing a chemical formula, the positive cation is always written before the negative anion. MgO magnesium oxide PREDICTING FORMULAS OF BINARY IONIC COMPOUND Formula for NaCl: All alkali metal chlorides have similar formula for their chlorides LiCl, KCl. For alkaline earth metals: If BaCl 2 is the chloride formed, then MgCl 2, CaCl 2 and SrCl 2 will also follow this pattern. 3

4 TERNARY IONIC COMPOUND A compound containing a metal and two other elements are classified as ternary ionic compound. It comprises of a monoatomic metal cation and a polyatomic oxyanion, example, NaNO3. The names of ternary ionic compounds usually have the suffix ate or ite. Example, KClO 3 Potassium Chlorate KClO 2 Potassium Chlorite If you have a transition metal, the charge needs to be determined first. BINARY MOLECULAR COMPOUNDS Binary molecular compound is composed of 2 nonmetals. A molecule is the simplest representative particle in a binary molecular compound. The following order is prescribed by IUPAC for writing the elements in a compound. C, P, N, H, S, I, Br, Cl, O, F Examples of binary compounds with hydrogen are as follows: CH 4, PH 3, NH 3, H 2 S, HI, HBr, HCl, H 2 O and HF NAMING BINARY MOLECULAR COMPOUNDS First element in the compound be named first The second element bears the suffix ide. The number of atoms of each element be indicated by Greek prefixes in the table below Atom Prefix Atom Prefix 1 mono 6 hexa 2 di 7 hepta 3 tri 8 octa 4 tetra 9 nona 5 penta 10 deca When you have two vowels in the name of a compound, the first vowel is dropped, examples, Monooxide, you write monoxide Tetraoxide, you write tetroxide. BINARY ACIDS Binary acids are aqueous solutions of compounds containing hydrogen and a nonmetal. A binary acid is produced by dissolving a binary molecular compound in water. Example, HF and HCl. 4

5 First, use the prefix hydro before the nonmetal stem. Next, add the suffix ic acid. Example, HCl (aq) Hydro + Chlor + ic acid = Hydrochloric acid H 2 S (aq) Hydro + Sulfur + ic acid = Hydrosulfuric acid TERNARY OXYACIDS Ternary oxyacids are aqueous solution of a compound containing hydrogen and oxyanion. Naming method is by attaching the suffix ic acid to the nonmetal stem of the oxyanion. Examples, HNO 3(aq) Nitric acid HNO 2(aq) Nitrous acid Ternary Oxyacids Polyatomic Oxyanion Sulfuric acid, H 2 SO 4(aq) 2 Sulfate ion, SO 4 Sulfurous acid, H 2 SO 3(aq) 2 Sulfite ion, SO 3 5