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Molecules and Compounds

Molecules and Compounds
Chapter 5 Molecules and Compounds www.ThesisScientist.comMolecules and Compounds • Salt  Sodium—shiny, reactive, poisonous.  Chlorine—pale yellow gas, reactive, poisonous.  Sodium chloride—table salt. • Sugar  Carbon—pencil or diamonds.  Hydrogen—flammable gas.  Oxygen—a gas in air.  Combine to form white crystalline sugar. www.ThesisScientist.comLaw of Constant Composition • All pure substances have constant composition. All samples of a pure substance contain the same elements in the same percentages (ratios). Mixtures have variable composition. www.ThesisScientist.comCompounds Display Constant Composition If we decompose water by electrolysis, we find 16.0 grams of oxygen to every 2.00 grams of hydrogen. Water has a constant mass ratio of oxygen to hydrogen of 8.0. mass of oxygen Mass Ratio  mass of hydrogen 16.0 g  8.0 2.0 g www.ThesisScientist.comPractice—Show that Hematite Has Constant Composition if a 10.0 g Sample Has 7.2 g Fe and the Rest Is Oxygen; and a Second Sample Has 18.1 g Fe and 6.91 g O. www.ThesisScientist.comExample 5.1—Show that Two Samples of Hematite Are Consistent with the Law of Constant Composition. Given: Sample 1: 7.2 g Fe, (10.07.2) = 2.8 g O; Sample 2: 18.1 g Fe, 6.91 g O Find: proportion Fe:O Solution Map: element masses compound composition composition = mass Fe : mass O Relationships: Solution: Sample 1 Sample 2 7.2 g Fe 18.1 g O  2.6 2.61 2.8 g O 6.91 g C Since both samples have the same Compare: proportion of elements, hematite shows www.ThesisScientist.com constant composition.Why Do Compounds Show Constant Composition • The smallest piece of a compound is called a molecule. • If you have a pure substance, then every molecule will have the same number and type of atoms. • Therefore, your compound have the same predictable properties (physical chemical). www.ThesisScientist.comFormulas Describe Compounds • Elements are represented by a letter symbol. • A pure compound is composed of atoms of two or more elements. • The number of each element is written to the right of the element as a subscript.  If there is only one atom, the 1 subscript is not written. • Polyatomic groups are placed in parentheses.  If more than one. www.ThesisScientist.comFormulas Describe Compounds, Continued Water = H O \ two atoms of 2 hydrogen and 1 atom of oxygen Table salt = NaCl, one sodium and one chlorine atom: notice that pure substances have consistent structures, these pure substance will also have consistent physical and chemical www.ThesisScientist.com properties.Order of Elements in a Formula • Metals are written first.  NaCl • Nonmetals are written in order from Table 5.1.  CO 2  There are occasional exceptions for historical or informational reasons. H O, but NaOH . 2 Table 5.1 Order of Listing Nonmetals C P N H S I Br Cl O F in Chemical Formulas www.ThesisScientist.comPractice—Write Formulas for Each of the Following Compounds. • Hematite—Composed of four oxide ions for every three iron ions. Fe O 3 4 • Acetone—Each molecule contains six hydrogen atoms, three carbon atoms, and one oxygen atom. C H O 3 6 www.ThesisScientist.comMolecules with Polyatomic Ions Symbol of the polyatomic Symbol of the polyatomic ion called nitrate. ion called sulfate. Mg(NO ) CaSO 3 2 4 Compound called Compound called magnesium nitrate. calcium sulfate. Implied ―1‖ subscript Implied ―1‖ subscript on magnesium. on calcium. Parentheses to group two NO s. No parentheses for one SO . 3 4 www.ThesisScientist.comMolecules with Polyatomic Ions, Continued Subscript indicating No subscript indicating two NO groups. 3 one SO group. 4 Mg(NO ) CaSO 3 2 4 Compound called Compound called magnesium nitrate. calcium sulfate. Implied ―1‖ subscript Implied ―1‖ subscript on nitrogen, total 2 N. on sulfur, total 1 S. Stated ―4‖ subscript Stated ―3‖ subscript on oxygen, total 4 O. www.ThesisScientist.com on oxygen, total 6 O.Practice—Determine the Total Number of Atoms or Ions in One Formula Unit of Each of the Following. • Mg(C H O ) 1 Mg + 4 C + 6 H + 4 O = 15 2 3 2 2 • (Hg ) (PO ) 6 Hg + 2 P + 8 O = 16 2 3 4 2 www.ThesisScientist.comClassifying Materials • Atomic elements = are single atoms. • Molecular elements = multiatom molecules. • Molecular compounds = molecules made of only nonmetals. • Ionic compounds = Compounds made of cations and anions. www.ThesisScientist.comMore about Molecular Elements • Certain elements occur as diatomic molecules. • 7 diatomic elements—The Rule of 7s Find the element with atomic number 7, N. Make a figure 7 by going over to Group 7A, then down. The seventh element is H . 2 7A 7 H N O F 2 2 2 2 Cl 2 Br 2 I 2 www.ThesisScientist.comMolecular Compounds • Two or more nonmetals. • Smallest unit is a molecule. www.ThesisScientist.comIonic Compounds • Metals + nonmetals. • No individual molecule units, instead have a 3dimensional array of cations and anions made of formula units. www.ThesisScientist.comMolecular View of Elements and Compounds www.ThesisScientist.comClassify Each of the Following as Either an Atomic Element, Molecular Element, Molecular Compound, or Ionic Compound, Continued. • Aluminum, Al = Atomic element. • Aluminum chloride, AlCl = Ionic compound. 3 • Chlorine, Cl = Molecular element. 2 • Acetone, C H O = Molecular compound. 3 6 • Carbon monoxide, CO = Molecular compound. • Cobalt, Co = Atomic element. www.ThesisScientist.comIonic Compounds • Ionic compounds are made of ions called cations and anions. Cations = + charged ions; anions = − charged ions. • The sum of the + charges of the cations must equal the sum of the − charges of the anions. + 2 + • If Na is combined with S , you will need 2 Na 2 ions for every S ion to balance the charges, therefore the formula must be Na S. 2 www.ThesisScientist.comWriting Formulas for Ionic Compounds 1. Write the symbol for the metal cation and its charge. 2. Write the symbol for the nonmetal anion and its charge. 3. Charge (without sign) becomes subscript for the other ion. 4. Reduce subscripts to smallest wholenumber ratio. 5. Check that the sum of the charges of the cation cancels the sum of the anions. www.ThesisScientist.comWrite the Formula of a Compound Made from Aluminum Ions and Oxide Ions. +3 1. Write the symbol for the metal Al column 3A cation and its charge. 2. Write the symbol for the 2 O column 6A nonmetal anion and its charge. 3. Charge (without sign) becomes +3 2 Al O subscript for the other ion. 4. Reduce subscripts to smallest Al O 2 3 wholenumber ratio. 5. Check that the total charge of Al = (2)∙(+3) = +6 the cations cancels the total O = (3)∙(2) = 6 charge of the anions. www.ThesisScientist.comPractice—What Are the Formulas for Compounds Made from the Following Ions + 3 Potassium ion with a nitride ion. K with N K N 3 +2 Calcium ion with a bromide ion. Ca with Br CaBr 2 +3 2 Aluminum ion with a sulfide ion. Al with S Al S 2 3 www.ThesisScientist.comPractice—What Are the Formulas for Compounds Made from the Following Ions 1. Copper(II) ion with a nitride ion. 2. Iron(III) ion with a bromide ion. www.ThesisScientist.comPractice─Name the Following Compounds. 4+ • Ti Cl 2+ • Pb Br 3+ 2 • Fe S www.ThesisScientist.comFormula Mass • The mass of an individual molecule or formula unit. • Also known as molecular mass or molecular weight. • Sum of the masses of the atoms in a single molecule or formula unit.  Whole = Sum of the parts. Mass of 1 molecule of H O 2 = 2(1.01 amu H) + 16.00 amu O = 18.02 amu. www.ThesisScientist.comPractice—Calculate the Formula Mass of Al 2 26.98 amu S 3 32.07 amu Al (SO ) 2 4 3 O 12 16.00 amu Al (SO ) 342.17 amu 2 4 3 Cr 1 52.01 amu H 2 1.00 amu C 2 12.01 amu Cr(HCO ) 3 2 O 6 16.00 amu Cr(HCO ) 174.03 amu 3 2 www.ThesisScientist.comEnd: if Lab is on nomenclature www.ThesisScientist.comFormulatoName Step 1 Is the compound one of the exceptions to the rules www.ThesisScientist.comCommon Names—Exceptions • H O = Water, steam, ice. 2 • NH = Ammonia. 3 • CH = Methane. 4 • NaCl = Table salt. • C H O = Table sugar. 12 22 11 www.ThesisScientist.comFormulatoName Step 2 What major class of compound is it Ionic or Molecular www.ThesisScientist.comMajor Classes • Ionic compounds.  Metal + nonmetal(s). Metal first in formula.  Binary ionic or compounds with polyatomic ions. • Molecular compounds.  2 or more nonmetals.  Binary molecular (or binary covalent). 2 nonmetals.  Acids—Formula starts with H. Though acids are molecular, they behave as ionic when dissolved in water. May be binary or oxyacid. www.ThesisScientist.comFormulatoName Step 3 What major subclass of compound is it Binary Ionic, Ionic with Polyatomic Ions, Binary Molecular, Binary Acid, or Oxyacid www.ThesisScientist.comClassifying Compounds • Compounds containing a metal and a nonmetal = Binary ionic.  Type I and II. • Compounds containing a polyatomic ion = Ionic with polyatomic ion. • Compounds containing two nonmetals = Binary molecular compounds. • Compounds containing H and a nonmetal = Binary acids. • Compounds containing H and a polyatomic ion = Oxyacids. www.ThesisScientist.comFormulatoName Step 4 Apply rules for the class and subclass. www.ThesisScientist.comFormulatoName Rules for Ionic • Made of cation and anion. • Name by simply naming the ions. If cation is: Type I metal = Metal name. Type II metal = Metal name (charge). Polyatomic ion = Name of polyatomic ion. If anion is: Nonmetal = Stem of nonmetal name + ide. Polyatomic ion = Name of polyatomic ion. www.ThesisScientist.comMonatomic Nonmetal Anion • Determine the charge from position on the periodic table. • To name anion, change ending on the element name to –ide. 4A = 4 5A = 3 6A = 2 7A = 1 C = Carbide N = Nitride O = Oxide F = Fluoride Si = Silicide P = Phosphide S = Sulfide Cl = Chloride www.ThesisScientist.comMetal Cations • Type I  Metals whose ions can only have one possible charge. 1A, 2A, (Al, Zn, Ag).  Determine charge by position on the periodic table. 1A = +, 2A = 2+, Al = 3+.  Some need to be memorized. Zn = 2+, Ag = +. • Type II How do you know a  Metals whose ions can have more than metal cation is Type II one possible charge.  Determine charge by charge on anion. www.ThesisScientist.comDetermine if the Following Metals are Type I or Type II. If Type I, Determine the Charge on the Cation it Forms. • Lithium, Li. • Copper, Cu. • Gallium, Ga. • Tin, Sn. • Strontium, Sr. www.ThesisScientist.comDetermine if the Following Metals are Type I or Type II. If Type I, Determine the Charge on the Cation it Forms, Continued. • Lithium, Li Type I 1+ • Copper, Cu Type II • Gallium, Ga Type I 3+ • Tin, Sn Type II • Strontium, Sr Type I 2+ www.ThesisScientist.comType I Binary Ionic Compounds • Contain metal cation + nonmetal anion. • Metal listed first in formula and name. 1. Name metal cation first, name nonmetal anion second. 2. Cation name is the metal name. 3. Nonmetal anion named by changing the ending on the nonmetal name to –ide. www.ThesisScientist.comExample—Naming Binary Ionic, Type I Metal, CsF 1. Is it one of the common exceptions H O, NH , CH , NaCl, C H O = No 2 3 4 12 22 11 2. Identify major class. Cs is a metal because it is on the left side of the periodic table. F is a nonmetal because it is on the right side of the periodic table. \ Ionic. 3. Identify the subclass. 2 elements, \ Binary ionic. 4. Is the metal Type I or Type II Cs is in Group 1A, \ Type I. www.ThesisScientist.comExample—Naming Binary Ionic, Type I Metal, CsF, Continued 5. Identify cation and anion. + Cs = Cs because it is Group 1A. F = F because it is Group 7A. 6. Name the cation. + Cs = cesium. 7. Name the anion. F = fluoride. 8. Write the cation name first, then the anion name. cesium fluoride. www.ThesisScientist.comPractice—Name the Following Compounds. • KCl • MgBr 2 • Al S 2 3 www.ThesisScientist.comPractice—Name the Following Compounds, Continued. • KCl potassium chloride. • MgBr magnesium bromide. 2 • Al S aluminum sulfide. 2 3 www.ThesisScientist.comType II Binary Ionic Compounds • Contain metal cation + nonmetal anion. • Metal listed first in formula and name. 1. Name metal cation first, name nonmetal anion second. 2. Metal cation name is the metal name followed by a roman numeral in parentheses to indicate its charge.  Determine charge from anion charge.  Common Type II cations in Table 5.5. 3. Nonmetal anion named by changing the ending on the nonmetal name to –ide. www.ThesisScientist.comDetermining the Charge on a Variable Charge Cation—Au S 2 3 1. Determine the charge on the anion. Au S the anion is S, since it is in Group 6A, its charge 2 3 is 2−. 2. Determine the total negative charge. Since there are 3 S in the formula, the total negative charge is −6. 3. Determine the total positive charge. Since the total negative charge is −6, the total positive charge is +6. 4. Divide by the number of cations. Since there are 2 Au in the formula and the total positive charge is +6, each Au has a 3+ charge. www.ThesisScientist.comExample—Writing Formula for a Binary Ionic Compound Containing Variable Charge Metal, Manganese(IV) Sulfide 1. Write the symbol for the cation +4 Mn and its charge. 2 2. Write the symbol for the anion S and its charge. +4 2 Mn S Mn S 3. Charge (without sign) becomes 2 4 subscript for the other ion. 4. Reduce subscripts to smallest MnS 2 wholenumber ratio. 5. Check that the total charge of Mn = (1)∙(+4) = +4 the cations cancels the total S = (2)∙(2) = 4 charge of the anions. www.ThesisScientist.comPractice—What Are the Formulas for Compounds Made from the Following Ions 1. Copper(II) ion with a nitride ion. 2. Iron(III) ion with a bromide ion. www.ThesisScientist.comPractice—What Are the Formulas for Compounds Made from the Following Ions, Continued 2+ 3 1. Cu with N Cu N 3 2 +3 2. Fe with Br FeBr 3 www.ThesisScientist.comExample—Naming Binary Ionic, Type II Metal, CuCl 1. Is it one of the common exceptions H O, NH , CH , NaCl, C H O = No 2 3 4 12 22 11 2. Identify major class. Cu is a metal because it is on the left side of the periodic table. Cl is a nonmetal because it is on the right side of the periodic table. \ Ionic. 3. Identify the subclass. 2 elements, \ Binary ionic. 4. Is the metal Type I or Type II Cu is not in Group 1A, 2A, or (Al, Zn, Ag) \ Type II. www.ThesisScientist.comExample—Naming Binary Ionic, Type II Metal, CuCl, Continued 5. Identify cation and anion. − Cl = Cl because it is Group 7A. + Cu = Cu to balance the charge. 6. Name the cation. + Cu = Copper(I). 7. Name the anion. − Cl = Chloride. 8. Write the cation name first, then the anion name. Copper(I) chloride. www.ThesisScientist.comPractice─Name the Following Compounds. • TiCl 4 • PbBr 2 • Fe S 2 3 www.ThesisScientist.comPractice─Name the Following Compounds, Continued. • TiCl Titanium(IV) chloride. 4 Cl = 4(−1) = −4 Ti = +4 = 1(4+) • PbBr Lead(II) bromide. 2 Br = 2(−1) = −2 Pb = +2 = 1(2+) • Fe S Iron(III) sulfide. 2 3 S = 3(−2) = −6 Pb = +6 = 2(3+) www.ThesisScientist.comCompounds Containing Polyatomic Ions • Polyatomic ions are single ions that contain more than one atom. • Name any ionic compound by naming cation first and then anion. Nonpolyatomic cations named like Type I and II. Nonpolyatomic anions named with –ide. www.ThesisScientist.comSome Common Polyatomic Ions Name Formula Name Formula – – Acetate C H O Hypochlorite ClO 2 3 2 2– – Carbonate CO Chlorite ClO 3 2 – Hydrogencarbonate Chlorate ClO 3 – HCO 3 (aka bicarbonate) – Perchlorate ClO 4 – Hydroxide OH 2– Sulfate SO 4 – Nitrate NO 2– 3 Sulfite SO 3 – Nitrite NO 2 Hydrogen sulfate – HSO 4 2– Chromate CrO (aka bisulfate) 4 2– Dichromate Cr O Hydrogen sulfite 2 7 – HSO 3 + (aka bisulfite) Ammonium NH 4 www.ThesisScientist.comExample—Writing Formula for an Ionic Compound Containing Polyatomic Ion, Iron(III) phosphate 1. Write the symbol for the cation +3 Fe and its charge. 3 2. Write the symbol for the anion PO 4 and its charge. +3 3 Fe PO Fe (PO ) 3. Charge (without sign) becomes 4 3 4 3 subscript for the other ion. 4. Reduce subscripts to smallest FePO 4 wholenumber ratio. 5. Check that the total charge of Fe = (1)∙(+3) = +3 the cations cancels the total PO = (1)∙(3) = 3 charge of the anions. 4 www.ThesisScientist.comPractice—What Are the Formulas for Compounds Made from the Following Ions 1. Aluminum ion with a sulfate ion. 2. Chromium(II) with hydrogencarbonate. www.ThesisScientist.comPractice—What Are the Formulas for Compounds Made from the Following Ions, Continued +3 2 1. Al with SO Al (SO ) 4 2 4 3 +2 ─ 2. Cr with HCO Cr(HCO ) 3 3 2 www.ThesisScientist.comPatterns for Polyatomic Ions 1. Elements in the same column form similar polyatomic ions.  Same number of Os and same charge. ClO = chlorate \ BrO = bromate. 3 3 2. If the polyatomic ion starts with H, the name adds hydrogen prefix before it and 1is added to the charge. 2 1 CO = carbonate \ HCO = hydrogencarbonate. 3 3 www.ThesisScientist.comPeriodic Pattern of Polyatomic Ions ate Groups 3A 4A 5A 6A 7A 2 1 3 CO NO BO 3 3 3 2 3 2 1 SiO PO SO ClO 3 4 4 3 3 2 1 AsO SeO BrO 4 4 3 2 1 TeO IO 4 3 www.ThesisScientist.comPatterns for Polyatomic Ions • ate ion. 1 Chlorate = ClO . 3 • ate ion + 1 O  same charge, per prefix. 1 Perchlorate = ClO . 4 • ate ion – 1 O  same charge, ite suffix. 1 Chlorite = ClO . 2 • ate ion – 2 O  same charge, hypo prefix, ite suffix. 1 Hypochlorite = ClO . www.ThesisScientist.comExample—Naming Ionic with Polyatomic Ion, Na SO 2 4 1. Is it one of the common exceptions H O, NH , CH , NaCl, C H O = No 2 3 4 12 22 11 2. Identify major class. Na is a metal because it is on the left side of the periodic table. SO is a polyatomic ion. 4 \ Ionic 3. Identify the subclass. Compound has 3 elements \ Ionic with polyatomic ion. 4. Is the metal Type I or Type II Na is in Group 1A, \ Type I. www.ThesisScientist.comExample—Naming Ionic with Polyatomic Ion, Na SO , Continued 2 4 5. Identify the ions. + Na = Na because in Group 1A. 2 SO = SO a polyatomic ion. 4 4 6. Name the cation. + Na = sodium (Type I). 7. Name the anion. 2 SO = sulfate. 4 8. Write the name of the cation followed by the name of the anion. sodium sulfate. www.ThesisScientist.comExample—Naming Ionic with Polyatomic Ion, Fe(NO ) 3 3 1. Is it one of the common exceptions H O, NH , CH , NaCl, C H O = No 2 3 4 12 22 11 2. Identify major class. Fe is a metal because it is on the left side of the periodic table. NO is a polyatomic ion because it is in ( ). 3 \ Ionic. 3. Identify the subclass. There are 3 elements \ Ionic with polyatomic ion. 4. Is the metal Type I or Type II Cu is not in Group 1A, 2A, or (Al, Zn, Ag) \ Type II. www.ThesisScientist.comExample—Naming Ionic with Polyatomic Ion, Fe(NO ) , Continued 3 3 5. Identify the ions. − NO = NO a polyatomic ion. 3 3 3+ − Fe = Fe to balance the charge of the 3 NO . 3 6. Name the cation. 3+ Fe = iron(III) (Type II). 7. Name the anion. − NO = nitrate. 3 8. Write the name of the cation followed by the name of the anion. iron(III) nitrate. www.ThesisScientist.comPractice─Name the Following 1. NH Cl 4 2. Ca(C H O ) 2 3 2 2 3. Cu(NO ) 3 2 www.ThesisScientist.comPractice─Name the Following, Continued 1. NH Cl Ammonium chloride. 4 2. Ca(C H O ) Calcium acetate. 2 3 2 2 3. Cu(NO ) Copper(II) nitrate. 3 2 NO = 2(−1) = −2 3 Cu = +2 = 1(2+) www.ThesisScientist.comFormulatoName Rules for Molecular • We will not learn the rules for molecular compounds with more than 2 elements. • For binary molecular: Name first nonmetal. Then name second nonmetal with ide ending. Then give each name a prefix to indicate its subscript in the formula. www.ThesisScientist.comBinary Molecular Compounds of Two Nonmetals 1. Name first element in formula first.  Use the full name of the element. 2. Name the second element in the formula with an −ide, as if it were an anion.  However, remember these compounds do not contain ions 3. Use a prefix in front of each name to indicate the number of atoms.  Never use the prefix mono on the first element. www.ThesisScientist.comSubscript—Prefixes • 1 = mono  Not used on first nonmetal. • 2 = di • 3 = tri • 4 = tetra • 5 = penta • 6 = hexa • 7 = hepta • 8 = octa • Drop last ―a‖ if name begins with vowel. www.ThesisScientist.comExample—Naming Binary Molecular, BF 3 1. Is it one of the common exceptions H O, NH , CH , NaCl, C H O = No 2 3 4 12 22 11 2. Identify major class. B is a nonmetal because it is on the right side of the periodic table. F is a nonmetal because it is on the right side of the periodic table. \ Molecular. 3. Identify the subclass. 2 elements, \ Binary molecular. www.ThesisScientist.comExample—Naming Binary Molecular, BF , Continued 3 4. Name the first element. boron. 5. Name the second element with an –ide. Fluorine  fluoride. 6. Add a prefix to each name to indicate the subscript. monoboron, trifluoride. 7. Write the first element with prefix, then the second element with prefix.  Drop prefix mono from first element. boron trifluoride. www.ThesisScientist.comFormulatoName Acids • Acids are molecular compounds that often behave like they are made of ions. • All names have acid at end. • Binary Acids = Hydro prefix + stem of the name of the nonmetal + ic suffix. • Oxyacids:  If polyatomic ion ends in –ate = Name of polyatomic ion with –ic suffix.  If polyatomic ion ends in –ite = Name of polyatomic ion with –ous suffix. www.ThesisScientist.comPractice─Name the Following • NO 2 • PCl 5 • I F 2 7 www.ThesisScientist.comPractice─Name the Following Continued • NO Nitrogen dioxide. 2 • PCl Phosphorus pentachloride. 5 • I F Diiodine heptafluoride. 2 7 www.ThesisScientist.comAcids + • Acids are molecular compounds that form H when dissolved in water. To indicate the compound is dissolved in water, (aq) is written after the formula. Not named as acid if not dissolved in water. • Sour taste. • Dissolve many metals. Like Zn, Fe, Mg, but not Au, Ag, Pt. • Formula generally starts with H. E.g., HCl, H SO 2 4. www.ThesisScientist.comAcids, Continued +1 • Contain H cation and anion. In aqueous solution. +1 • Binary acids have H cation and nonmetal anion. +1 • Oxyacids have H cation and polyatomic anion. www.ThesisScientist.comNaming Binary Acids • Write a hydro prefix. • Follow with the nonmetal name. • Change ending on nonmetal name to –ic. • Write the word acid at the end of the name. www.ThesisScientist.comExample—Naming Binary Acids, HCl 1. Is it one of the common exceptions H O, NH , CH , NaCl, C H O = No 2 3 4 12 22 11 2. Identify major class. First element listed is H, \ Acid. 3. Identify the subclass. 2 elements, \ Binary acid. www.ThesisScientist.comExample—Naming Binary Acids, HCl, Continued 4. Identify the anion. − Cl = Cl , chloride because Group 7A. 5. Name the anion with an –ic suffix. − Cl = chloride chloric 6. Add a hydro prefix to the anion name. hydrochloric 7. Add the word acid to the end. hydrochloric acid www.ThesisScientist.comNaming Oxyacids • If polyatomic ion name ends in –ate, then change ending to –ic suffix. • If polyatomic ion name ends in –ite, then change ending to –ous suffix. • Write word acid at end of all names. www.ThesisScientist.comExample—Naming Oxyacids, H SO 2 4 1. Is it one of the common exceptions H O, NH , CH , NaCl, C H O = No 2 3 4 12 22 11 2. Identify major class. First element listed is H, \ Acid. 3. Identify the subclass. 3 elements in the formula, \ Oxyacid. www.ThesisScientist.comExample—Naming Oxyacids, H SO ,Continued 2 4 4. Identify the anion. 2 SO = SO = sulfate. 4 4 5. If the anion has –ate suffix, change it to –ic. If the anion has –ite suffix, change it to –ous. 2 SO = sulfate sulfuric. 4 6. Write the name of the anion followed by the word acid. sulfuric acid (This is kind of an exception, to make it sound nicer) www.ThesisScientist.comExample—Naming Oxyacids, H SO 2 3 1. Is it one of the common exceptions H O, NH , CH , NaCl, C H O = No 2 3 4 12 22 11 2. Identify major class. First element listed is H, \ Acid. 3. Identify the subclass. 3 elements in the formula, \ Oxyacid. www.ThesisScientist.comExample—Naming Oxyacids, H SO , Continued 2 3 4. Identify the anion. 2 SO = SO = sulfite 3 3 5. If the anion has –ate suffix, change it to –ic. If the anion has –ite suffix, change it to –ous. 2 SO = sulfite sulfurous 3 6. Write the name of the anion followed by the word acid. sulfurous acid www.ThesisScientist.comPractice─Name the Following 1. H S 2 2. HClO 3 3. HNO 2 www.ThesisScientist.comPractice─Name the Following Continued 1. H S hydrosulfuric acid. 2 2. HClO chloric acid. 3 3. HNO nitrous acid. 2 www.ThesisScientist.comWriting Formulas for Acids • When name ends in acid, formulas starts with H. • Write formulas as if ionic, even though it is molecular. • Hydro prefix means it is binary acid, no prefix means it is an oxyacid. • For an oxyacid, if ending is –ic, polyatomic ion ends in –ate; if ending is –ous, polyatomic ion ends in –ous. www.ThesisScientist.comExample—Binary Acids, Hydrosulfuric Acid In all acids, the + 1. Write the symbol for the cation H + cation is H . and its charge. Hydro means 2 2. Write the symbol for the anion S binary. and its charge. + 2 H S H S 3. Charge (without sign) becomes 2 subscript for the other ion. 4. Add (aq) to indicate dissolved H S (aq) 2 in water. 5. Check that the total charge of H = (2)∙(+1) = +2 the cations cancels the total S = (1)∙(2) = 2 charge of the anions. www.ThesisScientist.comExample—Oxyacids, Carbonic Acid In all acids, the 1. Write the symbol for the cation + + cation is H . H and its charge. No hydro means 2 2. Write the symbol for the anion CO 3 polyatomic ion. and its charge. ic means ate ion. 3. Charge (without sign) becomes + 2 subscript for the other ion. H CO H CO 3 2 3 4. Add (aq) to indicate dissolved H CO (aq) in water. 2 3 5. Check that the total charge of H = (2)∙(+1) = +2 the cations cancels the total CO = (1)∙(2) = 2 charge of the anions. 3 www.ThesisScientist.comExample—Oxyacids, Sulfurous Acid In all acids, the 1. Write the symbol for the + + cation is H . H cation and its charge. No hydro means 2. Write the symbol for the 2 SO 3 polyatomic ion. anion and its charge. ous means ite ion. 3. Charge (without sign) becomes subscript for the + 2 H SO H SO 3 2 3 other ion. 4. Add (aq) to indicate H SO (aq) 2 3 dissolved in water. 5. Check that the total charge H = (2)∙(+1) = +2 of the cations cancels the SO = (1)∙(2) = 2 3 total charge of the anions . www.ThesisScientist.comPractice—What Are the Formulas for the Following Acids 1. Chlorous acid 2. Phosphoric acid 3. Hydrobromic acid www.ThesisScientist.comPractice—What Are the Formulas for the Following Acids, Continued + – 1. H with ClO HClO 2 2 + 3– 2. H with PO H PO 4 3 4 + – 3. H with Br HBr www.ThesisScientist.comFormulatoName Flowchart www.ThesisScientist.com
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