1. Use Lewis Symbols to show the reaction of Potassium and Sulfur atoms to produce the ionic compound Potassium Sulfide. Use arrows to indicate the appropriate movement of the valence electron(s) (5 points)

2. Draw Lewis Structures for the following molecules (6 points)

a) Ammonium Ion, NH₄+

b) Carbon monoxide, CO

3. Draw the Lewis Structure for Selenium Trioxide, SeO₃ (9 points)

4. For the following pairs of Lewis Structures indicate the value for the formal charge on each atom, and indicate which structure of the pair is most likely correct (11 points)

a)

b)

5. Draw the Lewis Structure for the following compounds (10 points)

a) IF₄^-

b) SI₅^-

6. Using the following bond dissociation energies calculate DH for the combustion of 2.0 moles of ethane. Be sure to write the balanced equation, and show all your work. (12 points)

D(C-H) = 414 kJ/mol

D(C-C) = 347 kJ/mol

D(O=O) = 498 kJ/mol

D(C=O) = 799 kJ/mol

D(O-H) = 464 kJ/mol

7. Draw the Lewis Structure for the molecule SI₄. What is the valence electron geometry of the central S atom? What is the molecular geometry of the SI₄ molecule? (9 points)

8. Which of the following molecular geometries would result in an overall molecular dipole for AB_n type molecules (where A and B are different types of atoms with different electronegativities) (8 points)

a) Linear

b) T-shaped

c) Trigonal Planar

d) Bent

9. Name the type of hybrid valence orbitals and draw an orbital diagram for the hydbrid orbitals for all the atoms in the following Lewis Structure of the NO₃^- ion. (12 points)

a) O

b) O

c) N

10. Draw the Lewis Structure of water. What is the valence electron geometry for the central Oxygen atom? What is the molecular geometry? What approximate angle(s) do you expect for the molecular geometry? (10 points)

11. Using the electronegativity values provided on the table at the end of the exam, predict whether the following bonds will be ionic, polar covalent or non-polar covalent (8 points)

a) C-H

b) C-S

c) S-Na

d) Si-O

12. EXTRA-EXTRA CREDIT (5 POINTS)

WHAT DID DR. BLABER EAT FOR THANKSGIVING?

13. EXTRA CREDIT (10 POINTS)

Using the following information draw a Born-Haber Cycle enthalpy diagram and determine the DH for the lattice energy of NaI(s):

Na⁺(g) + I^-(g) ® NaI(s)

Na(s) + ¹/₂I₂(s) ® NaI(s) DH = -288 kJ/mol

I₂(s) ® I₂(g) DH = +62 kJ/mol

Na(g) ® Na⁺(g) + e^- DH = +496 kJ/mol

I(g) + e^- ® I^-(g) DH = -295 kJ/mol

Na(s) ® Na(g) DH = +107 kJ/mol