Chapter 8 Covalent Bonding

Transcription

1 Tues 8.1 and 8.2 Chapter 8 Covalent Bonding Wed HW: Read 8.1 and 8.2 : #1-20 Lewis dot only More 8.2 VSEPR Theory Dot and Shape Lewis dot extension (packet pp 11-12) Thur HW: 21-39, 47 Resonance, and, hybrids Fri HW: read 8.3 # Bond polarity Polar bear comic strip Mon HW: Read 8.4 IMF s :determine polarity of Lewis dots # 8-20 Tues HW: polarity for all IMF s for all Network solids Review sheet Wed Thur Fri HW: # Review sheet IMF lab Finish lab (if needed) Go over review Test Objectives 8.1 Molecular Compounds made of only non-metals 1. Describe, in terms of electron behavior, covalent bonds. (p213) 2. Define molecule, molecular compounds, and molecular formulas. (p ) 3. Compare the properties of molecular compounds to ionic compounds. (p214) 4. Determine the number of atoms of each element indicated by a chemical formula. (p ) 8.2 The Nature of Covalent Bonding 5. Understand how the octet rule applies to covalent bonding. (p217) 6. Draw Lewis Dot structures (structural formulas) for covalent molecules and polyatomic ions including ones that exhibit resonance and are exceptions to the octet rule. (p ) 7. Rank single, double, and triple bonds by bond length or bond strength. 8. Define a coordinate covalent bond. (p223) 1

2 9. What is bond dissociation energy and what does it indicate about the strength of a bond? (p 226) 8.3 Bonding Theories 10. Define molecular orbitals. (p230) 11. Compare sigma and pi bonds. (p ) 12. Use the VESPR theory to determine the geometry of a molecule. (p ) 13. Determine the hybridization of the central atom of a molecule. (p ) 8.4 Polar Bonds and Molecules 14. Describe, in terms of electron behavior, polar bonds vs. non-polar bonds. (p ) 15. Classify bonds as non-polar covalent, polar covalent, or ionic based on the electronegativity difference of the elements forming the bond. (p238) 16. Identify molecules as being polar or non polar and use + and - symbols and an arrow to indicate the dipoles of a polar molecule. (p ) 17. Rank dispersion forces, dipole-dipole forces, and hydrogen bonding by relative strength. (p ) 18. Identify the type of IMF a material has by drawing the Lewis dot structure for it. 19. Relate the size of atoms or molecules to the magnitude of the dispersion forces they feel. 20. Define network solids and identify the types of bonding they have. Pulling Chapters 7 & 8 Together 21. Compare the types of binding forces of different materials in terms of melting and boiling point, and conductivity when dissolved or melted. 1. Ionic 2. Network Solid 3. Metallic 4. Molecular Hydrogen bonding Dipole-dipole Dispersion 2

3 Chapter 8 Practice 8.1 Molecular compounds 1. How are the melting and boiling points of molecular compounds different from those of ionic compounds? Much lower 2. List the 7 diatomic elements. H2, N2, O2, F2, Cl2, Br2, I2 3. How many atoms of each type are represented by the molecular formula for ethanol: C 2H6O? C 2 H-6 O-6 4. A covalent bond forms when two atoms _share a pair of electrons. 8.2 The Nature of Covalent Bonding 5. A dash in a Lewis dot structure represents _2 bonded_ electrons. 6. How many unshared pairs of electrons are in a water molecule? Draw it How many electrons are shared in a double bond? _4 A triple bond? _6 Molecule Lewis Dot Shape Polarity Hybrid IMF 8. pyramidal 107 PCl 3 9 CS 2 Linear 180 NP sp D 10. SBr 2 Bent Tetrahedral sp 3 D 109 SiF 2 Br COI 2 P sp 2 D 3

4 13. BCl CCl SiOH O 2 Chemistry Tetrahedral 109 Planar Linear 180 NP sp 2 D N P sp 2 D NP sp 2 D 17. PF 3 Pyramidal PO 4 3- Tetrahedral 109 N 19. AlCl 3 NP sp 2 D 20. SI 2 Bent 180 4

5 21. IO 3 - Chemistry Pyramidal H 2 Se Bent Linear NP sp D N BH CBr 4 Tetrahedral 109 NP sp 2 D N 26. BiH 3 Pyramidal HCl Linear 28 H 3 O + Pyramidal 107 H-bond 5

6 29. SO 4 2- Chemistry Tetrahedral 109 N 30. SiO 2 Linear 180 NP sp D 31. NCl 3 Pyramidal 107 N 32. BF 3 NP sp 2 D 33. HI Linear 34. CH 3 Cl Tetrahedral CF 2 O NP sp 2 D 36. NH 3 Pyramidal 107 H-bond 6

7 37. CO 2 Chemistry Linear 180 NP sp D 38. AlH 3 NP sp 2 D 39. OCl 2 Bent XeF 2 Linear 180 NP sp 3 d D 41. BrF 3 t-shaped 90 P sp 3 d D 42. XeF 4 Square 90 NP sp 3 d 2 D 43. Seesaw P sp 3 d D SF Seesaw P sp 3 d D SeH 4 7

8 45. XeCl 2 Chemistry Linear 180 NP sp 3 d D 46. PCl 6 - Octahedral 90 NP sp 3 d 2 D 47. PCl 5 bipyramidal 90, 120 NP sp 3 d D 48. ClF 5 Squarw based pyramid P sp 3 d 2 D 49. SeCl 6 Octahedral 90 NP sp 3 d 2 D 50. Pentagonal bipyramid NP sp 3 d 3 D IF ICl 3 t-shaped 90 P sp 3 d D 52. A covalent bond where the two electrons that form the bond are both contributed by one atom is called a bond. 53. If PH3 bonded with BH3, the P would bond with the B. Which atom would contribute the two electrons? 8

9 54. If a substance has a small dissociation energy, it means it has a relatively (strong/weak) covalent bond. 55. Draw the Lewis dot structures of the following molecules which exhibit resonance. a. NO 3 - b. SO 2 c. CO 3-2 d. NO What elements are common exceptions to the octet rule? (p ) Be, B, any after P Section 8.3 Bonding Theories 57. What is the difference in terms of electron location between a and a bond? σ directly between atoms π side by side overlap of vertical p orbitals 58. Complete the chart below: Lewis Dot Structure # of bonds # of bonds H2CO 3 1 CN H2 1 0 Section 8.4 Polar Bonds and Molecules 59. Determine the polarity for all of the molecules in #8-#39. Draw arrows and +/- signs on each drawing. 60. Dispersion is the attraction between particles that have temporary charges caused by normal movement of electrons. It is the (weakest/strongest) IMF. 61. Dipole-dipole attractions are between two molecules that are both _polar. 9

10 62. Hydrogen bonding occurs between two molecules that have the element _H_ attached to either _F, _O, or N. This IMF is the (strongest/weakest). 63. Determine the IMF that all the molecules exhibit for # What are the properties of network solids? 65. Why would it be harder to melt a network solid than a molecular solid? 66. In what ways are network solids like molecular solids? Answer in terms of the types of bonds inside them and in terms of their properties. 67. How are network solids similar to ionic solids? Answer in terms of particle arrangement and in terms of properties. 10

11 Lewis Dot Extention - Exceeding the Octet Rule Name: Draw the Lewis Dot structure for each molecule and name it s shape. 1. XeF 2 2. BrF 3 3. XeF 4 4. SF 4 5. SeH 4 6. XeCl 2 11

12 7. PCl 6-8. PCl 5 9. ClF SeCl IF ICl 3 12

13 Chapter 8 Review Contrast ionic bonds and covalent bonds. ionic metal and nonmetal, transfer of electrons covalent all nonmetals, sharing of electrons 2. List the 7 diatomic elements. H2, N2, O2, F2, Cl2, Br2, I2 3. Contrast the properties of molecular compounds with ionic compounds. molecular low melting point ionic- high melting point, brittle, conduct in solution and as a liquid. 4. Which of the following compounds is molecular? a) NaBr b) H2S c) AlCl3 d) CaO 5. Identify how many atoms of the underlined element are in the compounds listed. 3_a) CaCO3 4 b) H2SO4 1_c) H2CO3 9 d) Al(NO3)3 12_e) (NH4)3P How many electrons are shared in each type of bond? single bond double bond triple bond 7. Which type of bond in the problem above is a) strongest b) weakest a) b) 8. What is a lone pair (unshared pair)? 9. Which of the following is not a polyatomic ion? a) CO3 2- b) SO4 2- c) Co 2+ d) NH How are coordinate covalent bonds different from other covalent bonds? 11. Which would have a higher bond dissociation energy? a) O2 b) N2 12. Which would be harder to break apart? a) Substance A with bond dissociation value of 700 kj/mol b) Substance B with bond dissociation value of 800 kj/mol 13. Review the resonance structures worksheet. 13

14 Go back through your Chapter 8 worksheet and put a * by any substance that has an exception to the octet rule in its central atom. 15. What is a molecular orbital? 16. Give the number of σ and π bonds in each molecule. a) HCl σ and π b) O2 σ and π c) N2 σ and π 17. Explain in your own words what the VSEPR Theory is. 18. Review the Lewis Dot structures and hybrid columns on the Chapter 8 worksheet Determine if the following bonds would be polar covalent or non-polar covalent or ionic. a) H and Br b) Cs and Cl c) N and P d) O & O 20. Review the Chapter 8 worksheet where you determined if the molecule is polar or not. 21. Review the Chapter 8 worksheet where you determined the type of IMF each molecular substance has. 22. Which would have the greatest dispersion? a) C2H6 b) C3H8 c) C4H How is a network solid different from a molecular solid? 14

15 24. For the following descriptions use the following choices: a) dispersion b) dipole-dipole c) hydrogen bonding a. The force between SO2 molecules b. The force that makes HF a liquid at room temperatures c. The force which results from temporary, induced dipoles d. The type of force felt by H2 and F2 e. The type of IMF felt by the noble gases Tying Chapter 7 & 8 together: 25. Complete the following table: Ionic Metallic Molecular Network Solid Melting point (high/low) Boiling point (high/low) Physical room temp (solid/liquid/gas) Thermal /Electrical Conductivity (high/low) 26. At room temperature, substance A is a solid, substance B is a liquid and substance C is a gas. a) Which material has the greatest IMF? b) Which material is most orderly? c) Which is the best conductor of heat (thermal energy)? 15