1. Welcome to Chem 1C with Terri Bentzinger E-mail: benzene4president@gmail.combenzene4president@gmail.com Website: http://clas.sa.ucsb.edu/staff/terri/http://clas.sa.ucsb.edu/staff/terri/

2. Bonding – ch. 13/14 Chem 1C is Very conceptual – lots of memorizing

3. Bonding – ch. 13/14 1. Rank the following bonds in order of least polar to most polar: C-N C-O C-H C-Br

4. Bonding – ch. 13/14 Bond Polarity ⇒ uneven distribution of bonding electrons due to a difference in electronegativity H ⇒ 2.2 F ⇒ 4.0 Red ⇒ high electron density Purple ⇒ low electron density

5. Bonding – ch. 13/14 2. For each of the following draw the Lewis structure, determine the electronic and molecular geometries, predict the bond angle, state if polar or non polar and label the hybridization on the central atom. a. BF 3 b. HCN c. SO 2 d. POCl 3 e. I 3 - f. XeI 5 +

6. Bonding – ch. 13/14 3. Place the following molecules in order from smallest to largest H−N−H bond angles: NH 4 + NH 3 NH 2 –

7. Bonding – ch. 13/14 4. Rank the following in order of shortest to longest carbon-oxygen bond length: CO 3 2- CO 2 CO CH 3 OH

8. Bonding – ch. 13/14 5. Which of the following shows these molecules in order from most polar to least polar? CH 4, CF 2 Cl 2, CF 2 H 2, CCl 4, CCl 2 H 2 A) CH 4 > CF 2 Cl 2 > CF 2 H 2 > CCl 4 > CCl 2 H 2 B) CH 4 > CF 2 H 2 > CF 2 Cl 2 > CCl 4 > CCl 2 H 2 C) CF 2 Cl 2 > CF 2 H 2 > CCl 2 H 2 > CH 4 = CCl 4 D) CF 2 H 2 > CCl 2 H 2 > CF 2 Cl 2 > CH 4 = CCl 4 E) CF 2 Cl 2 > CF 2 H 2 > CCl 4 > CCl 2 H 2 > CH 4

9. Bonding – ch. 13/14 6. For the following structures: a. Fill in the missing bonds/electrons (if any) b. Label the hybridization for the carbons, nitrogen and oxygen atoms c. Assign the indicated angles d. Determine the number of sigma (σ) and pi (π) bonds e. Describe the indicated bonds ij k m l

10. Bonding – ch. 13/14 7. Which of the following resonance contributors for N 2 O is the most stable? Hint: calculate formal charges

11. Bonding – ch. 13/14 8. How many of the following molecules have all of their atoms in the same plane? F 2 O H 2 CONH 3 CO 2 C 2 H 4 BeCl 2 H 2 O 2

12. Bonding – ch. 13/14 9. Will all of the atoms in allene lie in the same plane?

13. Bonding – ch. 13/14 10. Fill in the following table: Molecule/Ion Electron Configuration Bond OrderMagnetism H2H2 He 2 + B2B2 CN – O2O2

14. Bonding – ch. 13/14 Molecular orbitals S with S P with P

15. Bonding – ch. 13/14 MO diagram for homonuclear molecules in Groups 1-5 MO diagram for homonuclear molecules in Groups 6-8

16. Bonding – ch. 13/14 σ2p*σ2p* π2p*π2p* π2pπ2p π2p*π2p* π2pπ2p σ2pσ2p σ2pσ2p σ2sσ2s σ2s*σ2s* σ2s*σ2s* σ2sσ2s Alligators Like to eat Beef BaCoN Period 2, groups 1-5 Hatchets chop OFf at the kNee Period 2, groups 6-8 σ2p*σ2p*

17. Bonding – ch. 13/14 11. Label the following molecular orbitals. A. D. B.E. C.

18. Bonding – ch. 13/14 12. Identify the element X if the ion X 2 - has the following valence electron configuration; (σ 3s ) 2 (σ 3s *) 2 (π 3p ) 4 (σ 3p ) 2 (π 3p *) 1

19. Bonding – ch. 13/14 13. Using the MO model predict the relative bond dissociation energy for the following: F 2 F 2 - F 2 +

20. Bonding – ch. 13/14 You have completed ch. 14

21. Bonding – ch. 13/14 – Answer Key 1. Rank the following bonds in order of least polar to most polar: C-N C-O C-H C-Br C-H < C-Br < C-N < C-O

22. Bonding – ch. 13/14 – Answer Key 2. For each of the following draw the Lewis structure, determine the electronic and molecular geometries, predict the bond angle, state if polar or non polar and label the hybridization on the central atom. a. BF 3 => EG/MG-trigonal planar, 120º, non-polar, sp 2 b. HCN => EG/MG-linear, 180º, polar, sp c. SO 2 => EG-trigonal planar, MG-bent, 120º, polar, sp 2 d. POCl 3 => EG/MG-tetrahedral, 109.5º, polar, sp 3 or sp 3 e. I 3 - => EG-trigonal bipyramid, MG-linear, 180º, non-polar, dsp 3 or sp 3 d f. XeI 5 + => EG-octahedral, MG-square planar, 90º, polar, d 2 sp 3 or sp 3 d 2

23. Bonding – ch. 13/14 – Answer Key 3. Place the following molecules in order from smallest to largest H−N−H bond angles: NH 4 + NH 3 NH 2 – NH 2 – < NH 3 < NH 4 + 4. Rank the following in order of shortest to longest carbon-oxygen bond length: CO 3 2- CO 2 CO CH 3 OH CO < CO 2 < CO 3 2- < CH 3 OH 5. Which of the following shows these molecules in order from most polar to least polar? D) CF 2 H 2 > CCl 2 H 2 > CF 2 Cl 2 > CH 4 = CCl 4

24. Bonding – ch. 13/14 – Answer Key 6. For the following structure: a. Fill in the missing bonds/electrons (if any) each nitrogen is missing 1 lone pair and each oxygen is missing 2 lone pairs b. Label the bonds as sigma (σ) or pi (π) single bonds are sigma, double bonds have one sigma and one pi, triple bonds have one sigma and two pi c. Label the hybridization for the carbons, nitrogens and oxygens. d. Assign the bond angles sp 3 sp 2 sp sp 3 sp 2 a. < 109.5° b. 120° c. <120° d. 120° e. 180° f. 120° g. <109.5° h. 109.5°

25. Bonding – ch. 13/14 – Answer Key 7. Which of the following resonance contributors for N 2 O is the most stable? Hint: calculate formal charges F.C. = 5-2-4 = -1 F.C. = 5-4-0 = +1 F.C. = 6-2-4 = 0 F.C. = 5-3-2 = 0 F.C. = 5-4-0 = +1 F.C. = 6-1-6 = -1 F.C. = 5-1-6 = -2 F.C. = 5-4-0 = +1 F.C. = 6-3-2 = +1 Most stable ⇒ Minimum magnitude of F.C. and (-) F.C. on most EN atom

26. Bonding – ch. 13/14 – Answer Key 8. How many of the following molecules have all of their atoms in the same plane? Molecules with 2 or 3 atoms automatically are planar – if there are 4 or more atoms you need to know the geometry – if there are 2 or more central atoms you need to know if they’re connected with a single bond which can rotate and cause atoms to move in and out of the plane or if they’re connected with a double or triple bond which can not rotate and therefore will lock the atoms into a set configuration F 2 O H 2 CONH 3 CO 2 C 2 H 4 BeCl 2 H 2 O 2

27. 9. Will all of the atoms in allene lie in the same plane? No Bonding – ch. 13/14 – Answer Key if central C is sp x all 3 Cs are on the x axis π can’t be x so let’s say y π can’t be x or y so z Since pi is z then it’s sp 2 xy Since pi is y then it’s sp 2 xz

28. Bonding – ch. 13/14 – Answer Key MoleculeElectron ConfigurationBond OrderMagnetism H2H2 (σ 1s ) 2 1diamagnetic He 2 + (σ 1s ) 2 (σ 1s *) 1 0.5paramagnetic B2B2 (σ 2s ) 2 (σ 2s *) 2 0paramagnetic CN - (σ 2s ) 2 (σ 2s *) 2 (π 2p ) 4 (σ 2p ) 2 3diamagnetic O2O2 (σ 2s ) 2 (σ 2s *) 2 (σ 2p ) 2 (π 2p ) 4 (π 2p *) 2 2paramagnetic 12. P 13. F 2 + > F 2 > F 2 - 10. 11. a. σ 1s * or σ 2s * b. σ 2p c. π 2p * d. σ 1s or σ 2s e. π 2p