INORGANIC CHEMISTRY 21-160-413 MIDTERM EXAM FALL 2006 10/30/2006Answer all questions in the blue book provided. Explain ALL your answers briefly,answers without an explanation will receive no credit. Total 100 pts.

1. �� Write down all relevant Lewis structures of the thiocyanate anion (SCN-) includingformal charges and determine which structure contributes most (explain your choice!).(5 points)

2. According to VSEPR theory determine the shape of the following molecules: (6 Points)a. XeO3F2b. BrF5c. SO2

3. The character table for the D4h point group has i and S4 symmetry elements amongothers, describe the operations associated with these elements? (3 points)

4. The 1H NMR spectrum of GeH4 is shown below, explain this spectrum, 73Ge is 7.8%abundant and has I = 9/2. (6 points)

5. Predict the structure of ClF3 and explain how the 19F NMR spectrum shown belowsupports your prediction, 19F is 100% abundant and has I = 1/2 (6 points)

6. Using Wade's rules predict the structures of the following. (2 points each)(a) B12H12

2-

(b) B4H10(c) [Ge10]2-

(d) C2B7H9(e) B10H14

7. Give the number and kind of interstitial holes for the following: (5 points)(a) Hexagonal Close-Packed:(b) Primitive Cubic:(b) Body-centered Cubic:

8. (a) The unit cell of a certain mineral is shown to the right. What is the name of the crystal lattice (mineral)? (1 point)

(b) Determine the stoichiometry of Ca:Ti:O in thislattice (the emipirical formula). Show the fullprocedure! (3 points)

(c) Determine the coordination number of Ca, Ti,and O in the lattice. (3 points)

9. (a) Explain the difference between a metal such as lithium and an intrinsicsemiconductor like silicon. Use an energy diagram to illustrate the differences. (4points)

(b) Give an example of an n-doped semiconductor. (2 points)

10. Give the major product for the air oxidation of: (3 points)(a) Lithium, (b) Sodium and (c) Potassium

11. (a) Draw the structure of borazine (B3N3H6) and determine the point group of themolecule. (4 points)(b) Explain, why borazine is sometimes also called "inorganic benzene". How is themolecule similar to benzene (point out at least 2 similarities)? (2 points)(c) How is borazine different from benzene (point out at least 2 differences)? (2 points)(d) How is boron nitride similar / different from graphite? (2 points)

12. The table below lists the electron configurations and ionization energies of the group 13elements. Using the electron configurations, explain the following trends in theionization energies.

(a) Why is the difference between IE1 and IE2 larger than the difference between IE2and IE3 for all the elements? (2 pts)(b) Why fourth ionization energy of B and Al so much bigger than that of the otherelements? (2 pts)(c) Explain the discontinuities in the values of IE2 and IE3 on going from Al to Ga andfrom In to Tl. (2 pts)(d) How do these trends in ionization energies affect the relative stabilities of oxidationstates 1 and 3 in compounds of these elements? (2 pts)(e) A similar trend is seen in group 14 where there are discontinuities in the values ofIE3 and IE4 on going from Si to Ge and from Sn to Pb. How does this affect the relativestabilities of the +2 and +4 oxidation states of Pb. (2 pts)

13. (a) Name two elements that are said to demonstrate the diagonal relationship in theperiodic table by their similarity of chemical properties. (2 points)

(b) List two of these similar chemical properties and show how they differ from thechemical properties of the other elements in the respective groups. (4 points)

14. (a) How do halogens act as Lewis acids to form charge transfer complexes? (3 points)(b) Rationalize the structure of the triiodide anion I3

- based on your answer to (a) (2 pts)

15. Suggest products for the reactions between the following:- (3 points each)(a) SbCl5 and PCl5(b) KF and AsF5

16. The 125Te NMR spectrum of [Me4N][TeF7] consists of a binomial octet (J = 2876 Hz)whereas the 19F NMR spectrum consists of a singlet with two superimposed doublets(of low intensity, J = 2876 and 2385 Hz). Explain these spectra and predict thestructure of the anion. 125Te is 7.0% abundant and has I = 1/2. 123Te is 0.9% abundantand has I = 1/2. 19F is 100% abundant and has I = 1/2. (6 points)