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Chemistry 2202 Chemical Bonding Review Answer the following in the space provided. 1. Classify the following substances given their physical properties. Substance (classify here) Physical Properties SATP State Boiling/Melting Pt. Electrical Conductivity Solubility in Water hard brittle solid extremely high not in any state no malleable solid high only as solid or liquid no colorless gas low not in any state yes brittle solid high only as liquid or aqueous yes 2. Sodium chloride and sugar have different bond types, yet these both dissolve in water. Explain. 3. Draw electron dot diagrams for the first 20 elements on the periodic table. What is the main difference between metals and non metals? 4. Give are the number of bonding electrons and lone pairs for each of the following atoms. ( H, C, Mg, He, O, P, N, Ca, Si ) 5. For each of the following, i) draw the appropriate Lewis electron dot diagram, ii) draw the structural diagram following the VSEPR theory, iii) indicate the polarity (polar or non- polar) and iv) describe the shape around each central atom. a. C2H5OH b. PH3 c. H2S d. CO2 e. C2H3Br 6. What is the difference between bond dipoles and molecular dipoles? Illustrate this difference using examples. 7. Two of the hardest substances known are diamond, Cn , and silicon carbide, SiC. Account for their extra-ordinary hardness in terms of the chemical bonds involved. 8. Why does chlorine have a higher boiling point than fluorine? Alkanes Boiling Pt. Alcohols Boiling Pt. methane, CH4(g) -161C methanol, CH3OH(l) 64.5C ethane, C2H6(g) -88.6C ethanol, C2H5OH(l) 78.5C propane, C3H8(g) -44.5C propanol, C3H7OH(l) 97.4C butane, C4H10(g) -0.5C butanol, C4H9OH(l) 117.3C pentane, C5H12(l) 36C hexane, C6H14(l) 69C Answer the following 3 questions by referring to the table above 9. CH3Cl(g) has a boiling point of -23.7C. a. Account for the difference in boiling point between CH3Cl(g) and propane. b. Account for the difference in boiling point between CH3Cl(g) and ethanol. 10. Hexanol, C6H13OH(l), has a boiling point of 156C. What prediction can we make about the boiling point of pentanol, C5H11OH(l)? Explain. 11. Ethene has the formula C2H4(g). What prediction can we make about its boiling point? Explain. 12. Which is more polar, hydrogen chloride or hydrogen fluoride? Why? 13. Can you tell which of the following compounds, C5H12 or CH3OH, has the larger boiling point? Why or why not? 14. Rank the following in order of increasing boiling point (lowest to highest) and explain why they are ranked that way. a. CH3Cl b. C3H8 c. C2H5OH d. SiC 15. Use bonding theory to explain the following phenomena. a. Ice floats in liquid water. b. A stream of water will bend when a charged object is brought close to it. c. A small needle can sit on the surface of water in a bowl without getting wet. d. Cooking oil will not mix with water. 16. Using electron dot diagrams, explain the formation of monatomic ions found in magnesium oxide. 17. Explain the difference in the information given by the formulas NaCl and NH3. 18. Explain why ionic compounds are brittle while metallic compounds are malleable and ductile. 19. Why does a metal conduct electricity in any phase while ionic compounds only conduct electricity in the liquid or aqueous phase but not as a solid? 20. Explain the following statement: “Although we classify compounds as ionic or molecular using the staircase line on the periodic table, there is no definite dividing line between ionic compounds and molecular compounds.” Chemical Bonding Terminology valence electrons electronegativity ionic bond covalent bond bonding electrons lone pairs bonding capacity single covalent bond double covalent bond triple covalent bond polar covalent bond nonpolar covalent bond bond dipole molecular dipole dispersion forces dipole-dipole forces hydrogen bonding network covalent bond ionic crystal lattice formula unit empirical formula metallic bond malleable ductile