Prentice-Hall © 2002 General Chemistry: Chapter 3 Slide 1 of 37 Philip Dutton University of Windsor, Canada Prentice-Hall © 2002 Chapter 3: Chemical Compounds General Chemistry Principles and Modern Applications Petrucci Harwood Herring 8 th Edition

Prentice-Hall © 2002 General Chemistry: Chapter 3 Slide 2 of 37 Contents 3-1Molecular and Ionic Compounds 3-2Molecular Mass 3-3Composition 3-4Oxidation States 3-5 Names and formulas Focus on Mass Spectrometry

Prentice-Hall © 2002 General Chemistry: Chapter 3 Slide 3 of 37 Molecular compounds

Prentice-Hall © 2002 General Chemistry: Chapter 3 Slide 4 of 37 Standard color scheme

Prentice-Hall © 2002 General Chemistry: Chapter 3 Slide 5 of 37 Some molecules H2O2H2O2 CH 3 CH 2 ClP 4 O 10 CH 3 CH(OH)CH 3 HCO 2 H

Prentice-Hall © 2002 General Chemistry: Chapter 3 Slide 6 of 37 Ionic compounds  Atoms of almost all elements can gain or lose electrons to form charged species called ions.  Compounds composed of ions are known as ionic compounds. ¾Metals tend to lose electrons to form positively charged ions called cations. ÖNon-metals tend to gain electrons to form negatively charged ions called anions.

Prentice-Hall © 2002 General Chemistry: Chapter 3 Slide 7 of 37 Sodium chloride Extended array of Na + and Cl - ions Simplest formula unit is NaCl

Prentice-Hall © 2002 General Chemistry: Chapter 3 Slide 8 of 37 Inorganic molecules S8S8 P4P4

Prentice-Hall © 2002 General Chemistry: Chapter 3 Slide 9 of 37 Molecular mass Molecular formula C 6 H 12 O 6 Empirical formulaCH 2 O Glucose 6 x x x Molecular Mass:Use the naturally occurring mixture of isotopes, = Exact Mass:Use the most abundant isotopes, 6 x x x =

Prentice-Hall © 2002 General Chemistry: Chapter 3 Slide 10 of 37 HalothaneC 2 HBrClF 3 M(C 2 HBrClF 3 ) = 2M C + M H + M Br + M Cl + 3M F = (2 x 12.01) (3 x 19.00) = g/mol Chemical Composition Mole ration C /n halothane Mass ratiom C /m halothane

Prentice-Hall © 2002 General Chemistry: Chapter 3 Slide 11 of 37 Example 3.4 Calculating the Mass Percent Composition of a Compound Calculate the molecular mass M(C 2 HBrClF 3 ) = g/mol For one mole of compound, formulate the mass ratio and convert to percent:

Prentice-Hall © 2002 General Chemistry: Chapter 3 Slide 12 of 37 Example 3-4

Prentice-Hall © 2002 General Chemistry: Chapter 3 Slide 13 of 37 Empirical formula 1.Choose an arbitrary sample size (100g). 2.Convert masses to amounts in moles. 3.Write a formula. 4.Convert formula to small whole numbers. 5.Multiply all subscripts by a small whole number to make the subscripts integral. 5 Step approach:

Prentice-Hall © 2002 General Chemistry: Chapter 3 Slide 14 of 37 Determining the Empirical and Molecular Formulas of a Compound from Its Mass Percent Composition. Dibutyl succinate is an insect repellent used against household ants and roaches. Its composition is 62.58% C, 9.63% H and 27.79% O. Its experimentally determined molecular mass is 230 u. What are the empirical and molecular formulas of dibutyl succinate? Step 1: Determine the mass of each element in a 100g sample. C g H 9.63 g O g Dibutyl succinate is an insect repellent used against household ants and roaches. Its composition is 62.58% C, 9.63% H and 27.79% O. Its experimentally determined molecular mass is 230 u. What are the empirical and molecular formulas of dibutyl succinate? Example 3-5

Prentice-Hall © 2002 General Chemistry: Chapter 3 Slide 15 of 37 Step 2: Convert masses to amounts in moles. Step 3: Write a tentative formula. Step 4: Convert to small whole numbers. C 5.21 H 9.55 O 1.74 C 2.99 H 5.49 O Example 3-5

Prentice-Hall © 2002 General Chemistry: Chapter 3 Slide 16 of 37 Step 5: Convert to a small whole number ratio. Multiply 2 to get C 5.98 H O 2 The empirical formula is C 6 H 11 O 2 Step 6: Determine the molecular formula. Empirical formula mass is 115 u. Molecular formula mass is 230 u. The molecular formula is C 12 H 22 O 4 Example 3-5

Prentice-Hall © 2002 General Chemistry: Chapter 3 Slide 17 of 37 Combustion analysis

Prentice-Hall © 2002 General Chemistry: Chapter 3 Slide 18 of 37 Oxidation States Metals tend to lose electrons. Na -> Na + + e - Non-metals tend to gain electrons. Cl + e - -> Cl - Reducing agentsOxidizing agents We use the Oxidation State to keep track of the number of electrons that have been gained or lost by an element.

Prentice-Hall © 2002 General Chemistry: Chapter 3 Slide 19 of 37 Rules for Oxidation States 1.The oxidation state (OS) of an individual atom in a free element is 0. 2.The total of the OS in all atoms in: i.Neutral species is 0. ii.Ionic species is equal to the charge on the ion. 3.In their compounds, the alkali metals and the alkaline earths have OS of +1 and +2 respectively. 4.In compounds the OS of fluorine is always –1

Prentice-Hall © 2002 General Chemistry: Chapter 3 Slide 20 of 37 Rules for Oxidation States 5.In compounds, the OS of hydrogen is usually +1 6.In compounds, the OS of oxygen is usually –2. 7.In binary (two-element) compounds with metals: i.Halogens have OS of –1, ii.Group 16 have OS of –2 and iii.Group 15 have OS of –3.

Prentice-Hall © 2002 General Chemistry: Chapter 3 Slide 21 of 37 Assigning Oxidation States. What is the oxidation state of the underlined element in each of the following? a) P 4 ; b) Al 2 O 3 ; c) MnO 4 - ; d) NaH a)P 4 is an element. P OS = 0 b)Al 2 O 3 : O is –2. O 3 is –6. Since (+6)/2=(+3), Al OS = +3. c)MnO 4 - : net OS = -1, O 4 is –8. Mn OS = +7. d)NaH: net OS = 0, rule 3 beats rule 5, Na OS = +1 and H OS = -1. Example 3-7

Prentice-Hall © 2002 General Chemistry: Chapter 3 Slide 22 of 37 Naming Compounds Trivial names are used for common compounds. A systematic method of naming compounds is known as a system of nomenclature. Organic compounds Inorganic compounds

Prentice-Hall © 2002 General Chemistry: Chapter 3 Slide 23 of 37 Inorganic Nomenclature Binary Compounds of Metals and Nonmetals NaCl=sodium chloride name is unchanged“ide” endingelectrically neutral MgI 2 =magnesium iodide Al 2 O 3 =aluminum oxide Na 2 S=sodium sulfide

Prentice-Hall © 2002 General Chemistry: Chapter 3 Slide 24 of 37

Prentice-Hall © 2002 General Chemistry: Chapter 3 Slide 25 of 37 Binary Compounds of Two Non-metals Molecular compounds usually write the positive OS element first. HCl hydrogen chloride mono1penta5 di2hexa6 tri3hepta7 tetra4octa8 Some pairs form more than one compound

Prentice-Hall © 2002 General Chemistry: Chapter 3 Slide 26 of 37

Prentice-Hall © 2002 General Chemistry: Chapter 3 Slide 27 of 37 Binary Acids Emphasize the fact that a molecule is an acid by altering the name. HClhydrogen chloridehydrochloric acid HFhydrogen fluoridehydrofluoric acid Acids produce H + when dissolved in water. They are compounds that ionize in water.

Prentice-Hall © 2002 General Chemistry: Chapter 3 Slide 28 of 37 Polyatomic Ions Polyatomic ions are very common. Table 3.3 gives a list of some of them. Here are a few: ammonium ionNH 4 + acetate ionC 2 H 3 O 2 - carbonate ionCO 3 2- hydrogen carbonateHCO 3 - hypochloriteClO - phosphatePO 4 3- chloriteClO 2 - hydrogen phosphateHPO 4 2- chlorateClO 3 - sulfateSO 4 2- perchlorateClO 4 - hydrogensulfateHSO 4 -

Prentice-Hall © 2002 General Chemistry: Chapter 3 Slide 29 of 37

Prentice-Hall © 2002 General Chemistry: Chapter 3 Slide 30 of 37 Naming Organic Compounds Organic compounds abound in nature Fats, carbohydrates and proteins are foods. Propane, gasoline, kerosene, oil. Drugs and plastics Carbon atoms form chains and rings and act as the framework of molecules.

Prentice-Hall © 2002 General Chemistry: Chapter 3 Slide 31 of 37

Prentice-Hall © 2002 General Chemistry: Chapter 3 Slide 32 of 37 Visualizations of some hydrocarbons

Prentice-Hall © 2002 General Chemistry: Chapter 3 Slide 33 of 37 Visualizations of some hydrocarbons

Prentice-Hall © 2002 General Chemistry: Chapter 3 Slide 34 of 37 Isomers Isomers have the same molecular formula but have different arrangements of atoms in space. H (c)

Prentice-Hall © 2002 General Chemistry: Chapter 3 Slide 35 of 37 Functional Groups – carboxylic acid

Prentice-Hall © 2002 General Chemistry: Chapter 3 Slide 36 of 37 Functional Groups - alcohol

Prentice-Hall © 2002 General Chemistry: Chapter 3 Slide 37 of 37 Chapter 3 Questions 3, 5, 12, 24, 35, 46, 53, 61, 57, 73, 95, 97