Intermolecular Attractions & the Properties of Liquids & Solids

Intermolecular Attractions & the Properties of Liquids & Solids CHAPTER 12 Chemistry: The Molecular Nature of Matter, 6th edition By Jesperson, Brady, & Hyslop REVIEW CHAPTER 12 Concept Review Strength of Intermolecular Forces London Dispersion Forces Dipole-Dipole Forces Weakest Hydrogen Bonds (a type of Dipole-Dipole Force) Ion-Dipole or Ion-Induced Dipole Forces!"#$"%#&'()*%+,-().-#/&$0)12"34#5%-6)72") 8&/"9:/+%);+5:%")&<)8+="%()>?)) Strongest @)

CHAPTER 12 Concept Review Strength of Intermolecular Forces London Dispersion Forces: minimized surface area London Dispersion Forces: maximized surface area Dipole-Dipole Forces: small overall dipole moment Dipole-Dipole Forces: large overall dipole moment Hydrogen Bonds: with 1 H-bond per molecule Hydrogen Bonds: with multiple H-bonds per molecule Ion-Dipole or Ion-Induced Dipole Forces Weakest Strongest!"#$"%#&'()*%+,-().-#/&$0)12"34#5%-6)72") 8&/"9:/+%);+5:%")&<)8+="%()>?)) A) CHAPTER 12 Concept Review Strength of Intermolecular Forces Table 12.3 Intermolecular Attraction London dispersion forces Dipole dipole attractions Hydrogen bonding Ion dipole attractions Ion induced dipole attractions Summary of Intermolecular Attractions Types of Substances that Exhibit Attraction All atoms, molecules, and ions experience these kinds of attractions. They are present in all substances. Occur between molecules that have permanent dipoles (i.e., polar molecules). Occurs when molecules contain N H, F H, and O H bonds. Occur when ions interact with polar molecules. Occur when an ion creates a dipole in a neighboring particle, which may be a molecule or another ion. Strength Relative to a Covalent Bond Depends on sizes and shapes of molecules. For large molecules, the cumulative effect of many weak attractions can lead to a large net attraction. 1 5% 5 10% About 10%; depends on ion charge and polarity of molecule. Variable, depending on the charge on the ion and the polarizability of its neighbor.!"#$"%#&'()*%+,-().-#/&$0)12"34#5%-6)72") 8&/"9:/+%);+5:%")&<)8+="%()>?)) B)

Property of s, l, g Increases Decreases Example Boiling Point Melting Point 1&3$%"##4C4/45-) D4E:#4&') F"5"'G&')&<)H)I) J2+$") J:%<+9")7"'#4&') K"L'M) H4#9&#45-) Property of s, l, g Increases Decreases Example Boiling Point Melting Point 1&3$%"##4C4/45-) D4E:#4&') F"5"'G&')&<)H)I) J2+$") J:%<+9")7"'#4&') K"L'M) H4#9&#45-) increasing total intermolecular forces increasing total intermolecular forces 4'9%"+#4'M),4#5+'9") C"5N""')9&//4#4&'#)N452) &52"%)$+%G9/"#)) N452)4'9%"+#4'M)Q4'"G9) "'"%M-)I)4'9%"+#",),4#5+'9")C"5N""') 9&//4#4&'#) decreasing total intermolecular forces decreasing total intermolecular forces,"9%"+#4'm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ater has a high boiling point because it has H-bonding, dipole, and dispersion forces. It is close to heptane (C7H16), a heavier molecule that only experiences dispersion forces. The melting point of ionic solids is extremely high compared to water which experiences all other intermolecular forces, but not ion-dipole forces. (NaCl is 1074 K and water is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Equilibrium & Phase Diagrams 7 d )e)fgh1) T d )e)aai)+53) ) 7&)4'9%"+#") 7 @ )e)diih1) 72")#-#5"3)3:#5) %"#$&',)C-)4'9%"+#4'M)) T @ )e)f>i)5&)%"#5&%") "R:4/4C%4:36) o 7)4#)24M2"%) o H&/:3")&<)/4R:4,)4#) /&N"%)) o T)&<)P+$&%)24M2"%) ) ) 9 Le Chatelier s Principle S<)-&:)4'9%"+#")"452"%)52")/4R:4,) &%)52")2"+5)52")%"+9G&')4#),%4P"')5&)52")%4M25)5&)%"a "#5+C/4#2)"R:4/4C%4:30) S<)-&:)4'9%"+#")P+$&%)52") %"+9G&')N4//)C"),%4P"')5&)52") /"j)5&)%"a"#5+c/4#2)"r:4/4c%4:30)

3-D Simple Cubic Lattice Unit Cell Portion of lattice open view 11 Space filling model Other Cubic Lattices Face Centered Cubic Body Centered Cubic 12

Counting Atoms in Unit Cells Site Counts as Shared by X unit cells Body 1 1 Face 1/2 2 Edge 1/4 4 Corner 1/8 8 Interpreting Diffraction Data Bragg Equation n"=2d sin# n = integer (1, 2, $)! = wavelength of X rays d = interplane spacing in crystal! = angle of incidence and angle of reflectance of X rays to various crystal planes 14

Example: Using Diffraction Data X-ray diffraction measurements reveal that copper crystallizes with a face-centered cubic lattice in which the unit cell length is 362 pm. What is the radius of a copper atom expressed in picometers? This is basically a geometry problem. 15 Ex. Using Diffraction Data (cont.) Pythagorean theorem: a 2 + b 2 = c 2 Where a = b = 362 pm sides and c = diagonal 2a 2 = c 2 and c = 2a 2 = 2a diagonal = 2! (362 pm) = 512 pm diagonal = 4 " r Cu = 512 pm r Cu = 128 pm 16