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- 1. Copyright © 2011 Pearson Canada Inc.General Chemistry: Chapter 3Slide 1 of 32 PHILIP DUTTON UNIVERSITY OF WINDSOR DEPARTMENT OF CHEMISTRY AND BIOCHEMISTRY TENTH EDITION GENERAL CHEMISTRY Principles and Modern Applications PETRUCCI HERRING MADURA BISSONNETTE Chemical Compounds 3
- 2. Chemical Compounds Copyright © 2011 Pearson Canada Inc.General Chemistry: Chapter 3Slide 2 of 32
- 3. 3-1 Types of Chemical Compounds and Their Formulas Copyright © 2011 Pearson Canada Inc.General Chemistry: Chapter 3Slide 3 of 32 Molecular Compounds
- 4. Molecular compounds Copyright © 2011 Pearson Canada Inc.General Chemistry: Chapter 3Slide 4 of 32 Figure 3-1 Several representations of the compound acetic acid 1 Å/inch 0.4 Å/cm
- 5. Visualizations of (a) butane, (b) methylpropane, and (c) testosterone Figure 3-2 Copyright © 2011 Pearson Canada Inc.General Chemistry: Chapter 3Slide 5 of 32
- 6. Color scheme for use in molecular models Figure 3-3 Copyright © 2011 Pearson Canada Inc.General Chemistry: Chapter 3Slide 6 of 32
- 7. Ionic Compounds Copyright © 2011 Pearson Canada Inc.General Chemistry: Chapter 3Slide 7 of 32 • 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. + Metals tend to lose electrons to form positively charged ions called cations. - Non-metals tend to gain electrons to form negatively charged ions called anions.
- 8. Portion of an ionic crystal and a formula unit of NaCl FIGURE 3-4 Copyright © 2011 Pearson Canada Inc.General Chemistry: Chapter 3Slide 8 of 32 An extended array of Na+ and Cl- ions The simplest formula unit is NaCl
- 9. 3-2 The Mole Concept and Chemical Compounds Copyright © 2011 Pearson Canada Inc.General Chemistry: Chapter 3Slide 9 of 32 Formula mass the mass of a formula unit in atomic mass units (u) Molecular mass a formula mass of a molecular compound Weighted average mass add up the weighted average atomic masses Exact Mass add up the isotopic masses (see mass spectrometry) KEEP IN MIND that although molecular mass and molar mass sound similar and are related, they are not the same. Molecular mass is the weighted-average mass of one molecule expressed in atomic mass units, u. Molar mass is the mass of Avogadro’s number of molecules expressed in grams per mole, The two terms have the same numerical value but different units. g/mol.
- 10. Molecular forms of elemental sulfur and phosphorus Figure 3-5 Copyright © 2011 Pearson Canada Inc.General Chemistry: Chapter 3Slide 10 of 32
- 11. 3-3 Composition of Chemical Compounds Copyright © 2011 Pearson Canada Inc.General Chemistry: Chapter 3Slide 11 of 32 Halothane C2HBrClF3 Mole ratio nC/nhalothane Mass ratio mC/mhalothane M(C2HBrClF3 ) = 2MC + MH + MBr + MCl + 3MF = (2 x 12.01) + 1.01 + 79.90 + 35.45 + (3 x 19.00) = 197.38 g/mol
- 12. Establishing Formulas from Experimentally Determined Percent Composition of Compounds Copyright © 2011 Pearson Canada Inc.General Chemistry: Chapter 3Slide 12 of 32 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:
- 13. Combustion Analysis Copyright © 2011 Pearson Canada Inc.General Chemistry: Chapter 3Slide 13 of 32
- 14. Apparatus for combustion analysis Figure 3-6 Copyright © 2011 Pearson Canada Inc.General Chemistry: Chapter 3Slide 14 of 32
- 15. Copyright © 2011 Pearson Canada Inc.General Chemistry: Chapter 3Slide 15 of 32 3-4 Oxidation States: A Useful Tool in Describing Chemical Compounds Metals tend to lose electrons. Na Na+ + e- Non-metals tend to gain electrons. Cl + e- Cl- Reducing agents Oxidizing agents We use the Oxidation State to keep track of the number of electrons that have been gained or lost by an element.
- 16. Copyright © 2011 Pearson Canada Inc.General Chemistry: Chapter 3Slide 16 of 32
- 17. 3-5 Naming Compounds: Organic and Inorganic Compounds Copyright © 2011 Pearson Canada Inc.General Chemistry: Chapter 3Slide 17 of 32 Figure 3-7 Two oxides of lead Lead (IV) oxide Lead (II) oxide
- 18. Copyright © 2011 Pearson Canada Inc.General Chemistry: Chapter 3Slide 18 of 32 3-6 Names and Formulas of Inorganic Compounds Binary Compounds of Metals and Nonmetals
- 19. Copyright © 2011 Pearson Canada Inc.General Chemistry: Chapter 3Slide 19 of 32
- 20. Binary Compounds of Two Non-Metals Copyright © 2011 Pearson Canada Inc.General Chemistry: Chapter 3Slide 20 of 32 Molecular compounds usually write the positive OS element first. HCl hydrogen chloride mono 1 penta 5 di 2 hexa 6 tri 3 hepta 7 tetra 4 octa 8 Some pairs form more than one compound
- 21. Copyright © 2011 Pearson Canada Inc.General Chemistry: Chapter 3Slide 21 of 32
- 22. Binary Acids Copyright © 2011 Pearson Canada Inc.General Chemistry: Chapter 3Slide 22 of 32 Acids produce H+ when dissolved in water. They are compounds that ionize in water. The symbol (aq) signifies aqueous solution. H2S(aq) = hydrosulfuric acid HI(aq) = hydroiodic acid HCl(aq) = hydrochloric acid HBr(aq) = hydrobromic acid HF(aq) = hydrofluoric acid
- 23. Polyatomic Ions Copyright © 2011 Pearson Canada Inc.General Chemistry: Chapter 3Slide 23 of 32 Increasing oxidation state of nonmetal hypo___ite ___ite ___ate per___ate Increasing number of oxygen atoms :
- 24. Copyright © 2011 Pearson Canada Inc.General Chemistry: Chapter 3Slide 24 of 32
- 25. Copyright © 2011 Pearson Canada Inc.General Chemistry: Chapter 3Slide 25 of 32
- 26. Some Compounds of Greater Complexity Copyright © 2011 Pearson Canada Inc.General Chemistry: Chapter 3Slide 26 of 32 Figure 3-8 Effect of moisture on CoCl2 %H2O = 6 mol H2O 18.02 g H2O 1 mol H2O x 237.9 g CoCl2• 6 H2O x 100% = 45.45% H2O Effect of Moisture Blue anhydrous CoCl2 Pink hexahydrate CoCl2• 6 H2O
- 27. Copyright © 2011 Pearson Canada Inc.General Chemistry: Chapter 3Slide 27 of 32 3-7 Names and Formulas of Organic Compounds Organic compounds abound in nature Fats, carbohydrates and proteins are foods. Propane, gasoline, kerosene, oil are fuels. Drugs and plastics are produced by chemical industries. Carbon atoms form chains and rings and act as the framework of molecules.
- 28. Hydrocarbons Copyright © 2011 Pearson Canada Inc.General Chemistry: Chapter 3Slide 28 of 32 Figure 3-9 Visualizations of some hydrocarbons
- 29. Copyright © 2011 Pearson Canada Inc.General Chemistry: Chapter 3Slide 29 of 32 Isomers Isomers have the same molecular formula but have different arrangements of atoms in space. Are the following pairs isomers? H (c)
- 30. Functional Groups Copyright © 2011 Pearson Canada Inc.General Chemistry: Chapter 3Slide 30 of 32 Visualizations of some alcohols Figure 3-10
- 31. The carboxyl group and visualizations of two carboxylic acids Figure 3-11 Copyright © 2011 Pearson Canada Inc.General Chemistry: Chapter 3Slide 31 of 32
- 32. Copyright © 2011 Pearson Canada Inc.General Chemistry: Chapter 3Slide 32 of 32 End of Chapter Questions Individuals have individual learning styles. You may have more than one style for different types of learning. Take notes and actively listen. Participate in your learning process! Seeing Reading Listening Writing
Editor's Notes
- In this chapter, you will learn how to deduce and write chemical formulas and how to use the information incorporated into chemical formulas. The chapter ends with an overview of the relationship between names and formulas—chemical nomenclature.
- Scanning electron microscope image of sodium chloride crystals. Chemical compounds, their formulas, and their names are topics discussed in this chapter.
- A molecular compound is made up of discrete units called molecules, which typically consist of a small number of nonmetal atoms held together by covalent bonds. Molecular compounds are represented by chemical formulas, symbolic representations that, at minimum, indicate • the elements present • the relative number of atoms of each element
- Chemical formula – relative numbers of atoms of each element present Empirical formula – the simplest whole number formula Structural formula – the order and type of attachements – shows multiple bonds - may show lone pairs - hard to show 3-d In the molecular model, the black spheres are carbon, the red are oxygen, and the white are hydrogen. To show that one H atom in the molecule is fundamentally different from the other three, the formula of acetic acid is often written as HC2H3O2 or (see Section 5-3). To show that this H atom is bonded to an O atom, the formulas CH3CO2H and CH3COOH are also used. For a few chemical compounds, you may find different versions of chemical formulas in different sources.
- The sizes of atoms, reflected in the various sizes of the colored spheres, are related to the locations of the elements in the periodic table, as discussed in Section 9-3.
- Positive and negaive ions joined together by electrostatic forces Metals tend to lose electrons to form cations Non-metals tend to gain electrons to form anions Ionic solids formulae are reported as the formula unit – inappropriate to call it a molecular formula
- Na loses one electron to form the sodium ion Cl gains one electron to form the chloride ion Centers of ions are shown in the ball and stick model for clarity Space filling model shows how the ions are actually in contact with one another. We will discuss face centered cubic and other types of packing in chapter 13
- In a sample of solid sulfur, there are eight sulfur atoms in a sulfur molecule. In solid white phosphorus, there are four phosphorus atoms per molecule. They come in various forms called allotropes – these are one allotrope of each
- Molecular formula tells us there are TWO moles of C per mole of halothane. We also know about the MASSES of the compound and its elemental components. Therefore we can talk about PERCENT COMPOSITION BY MASS
- If you know the molecular wt it is beneficial to choose that number, then only first three steps are required.
- Water vapour absorbed by magnesium perchlorate Carbon dioxide absorbed by sodium hydroxide. The differences in mass of the absorbers before and after yiled the masses of water and CO2 produced in the reaction Combustion takes place in an excess of oxygen so you cannot measure oxygen. Oxygen CAN be analyzed separately but is usually determined by difference.
- (a) Oxygen gas passes through the combustion tube containing the sample being analyzed. This portion of the apparatus is enclosed in a high-temperature furnace. Products of the combustion are absorbed as they leave the furnace—water vapor by magnesium perchlorate, and carbon dioxide gas by sodium hydroxide (producing sodium carbonate). The differences in mass of the absorbers, after and before the combustion, yield the masses of H2O and CO2 produced in the combustion reaction. (b) A molecular picture of the combustion of ethanol. Each molecule of ethanol produces two molecules CO2 and three H2O molecules. Combustion takes place in an excess of oxygen, so that oxygen molecules are present at the end of the reaction. Note the conservation of mass.
- Metals are electron sources Non-metals are electron sinks Sodium goes to the +1 oxidation state Chlorine goes tot eh –1 oxidation state
- These two compounds contain the same elements— lead and oxygen—but in different proportions. Their names and formulas must convey this fact: lead(IV) oxide = PbO2 (red-brown); lead(II) oxide = PbO (yellow).
- Write the unmodified name of the metal Then write the name of the nonmetal, modifed to end in ide. Ionic compounds must be electrically neutral
- In naming binary acids we use the prefix hydro- followed by the name of the other nonmetal modified with an -ic ending. The most important binary acids are listed below.
- 1. Polyatomic anions are more common than polyatomic cations. The most familiar polyatomic cation is the ammonium ion NH4 +. 2. Very few polyatomic anions carry the -ide ending in their names. Of those listed, only OH- (hydroxide ion) and CN- (cyanide ion) do. The common endings are -ite and -ate, and some names carry prefixes, hypo- or per-. 3. An element common to many polyatomic anions is oxygen, usually in combination with another nonmetal. Such anions are called oxoanions. 4. Certain nonmetals (such as Cl, N, P, and S) form a series of oxoanions containing different numbers of oxygen atoms. Their names are related to the oxidation state of the nonmetal atom to which the O atoms are bonded, ranging from hypo- (lowest) to per- (highest) according to the following scheme.
- Learn the most common ions first. When you understand the scheme on the previous slide, the names of several others will become obvious. Over time, the rest will become more familiar to you
- Most oxoacids are ternary compounds composed of hydrogen, oxygen and one other nonmental. Oxoacids are molecular compounds, salts are ionic compounds Ic and ate names are assigned to compounds (rather than ite and ate as in the oxoanions) in which the central nonmetal atom has an oxidation state equal to the periodic group number – 10 For halogens ic and ate names are assigned to compounds in which the halogen has an oxidation state of +5.
- The piece of filter paper was soaked in a water solution of cobalt(II) chloride and then allowed to dry. When kept in dry air, the paper is blue in color (anhydrous CoCl2). In humid air, the paper changes to pink (CoCl2 • 6 H2O).
- These are structural isomers. The structures are different these molecules do not have the same formula, they are different c) Now these molecules have the same formula and ALSO the same connectivity. These are geometric isomers.