DESCRIPTIVE INORGANIC CHEMISTRY March 24, 2011 INSTRUCTIONS: PRINT YOUR NAME > NAME.

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1 DESCRIPTIVE INORGANIC CHEMISTRY QUIZ II March 24, 2011 INSTRUCTIONS: PRINT YOUR NAME > NAME. SHOW YOUR WORK FOR PARTIAL CREDIT THE LAST PAGE IS A Periodic Table Work 5 of these (40 pts) R = lit-atm/mol-k 1 (8) R = J/mol-K 2 (8) h = X J-s 3 (8) c = X 10 8 m/s 4 (8) J = (kg-m 2 )/s 2 5 (8) 6 (8) 7 (8) Work 4 of these (60 pts) 8 (15) 9 (15) 10 (15) 11 (15) 12 (15) l TOTAL(100)

2 1. (a) Sketch a layer of a simple cubic packing arrangement of spheres, and describe where the next layer goes in relation to the layer you drew. Why is this arrangement not used in the packing of metals in crystals? 2. There are two types of most efficient packing of spheres. These are generally described by abababababa and abcabcabcabc. a) Indentify these two modes of packing., and b) Explain the abababababa and abcabcabcabc notation. c) Which goes with which description. 3. In ionic compounds the structure is often described as closest packed arrays of anions with cations filling holes in the structure. On the two diagrams below, use dotted circles to sketch the next layer, and clkearly indicate the locations of the two types of holes. Tetrahedral hole Octahedral hole

3 4. (a) Sketch the cesium chloride structure. (b) What is the coordination number of the cesium ion. (c) Calcium sulfide also has a ratio of 1:1 for the cation:anion ratio, but it has a sodium chloride like structure. Why is it that CaS does not adopt the CsCl structure. 5. Draw the three main resonance structures for the carbonate ion and estimate the C-O bond order.

4 6. The melting point for Manganese oxides are given below Manganese(II)oxide MnO 1945 ºC Manganese(III)oxide Mn 2 O ºC Manganese(IV)oxide MnO ºC Manganese(VII)oxide Mn 2 O 7 6 ºC (Explain why the melting decreases going down the series. Why is there such a large jump from the melting point of Manganese(IV)oxide to the melting point of Manganese(IV)oxide? 7. Which do you expect to have the higher melting point K 2 S of KCl? Explain why?

5 8. Fulminate ion, CNO -, forms unstable compounds with mamny being explosive. Draw three Lewis structure for this ion, and assign formal charges. Why is thios ion unstable?.

6 9. Below is the bond triangle discussed in the text: Place the following compounds in the correct position on the chart. MgO Al 2 O 3 SiO 2 CO 2 CuZn How would you describe the bonding in each of these compounds? Electronegativities Mg Al Si Cu Zn C O MgO Al 2 O 3 SiO 2 CO 2 CuZn

7 10. (a) Sketch the molecular orbital diagram for appropriate for O 2, O 2 - and O They all use the same diagram. (b) Calculate the bond order for each species. (c) What is the relative order of bond length? (shortest first) < < (d) What is the relative order of bond length? (weakest first) < < (e) NO - has a different molecular orbital diagram. Sketch this diagram, and determine the bond order. (f) sketch the lowest bonding orbital for O2 and for NO- showing how they differ. O O N O

8 11. Draw a valid Lewis sturucture for the following species. Determine the shape according to VSEPR. Assign formal charges to ions. PF 3 BrF 5 BH 4 - ClO 2 - HCN COF 2 (C atom central) (C atom central)

9 12. The structure below is an alloy of iron (Fe) and tin (Sn). The Iron atoms are shown as blue spheres and the tin atoms are shown as green spheres. The tin atoms are all completely contained in the cell. The iron atom occupy: Each corner of the cell The top and bottom faces of the cell The four vertical edges of the cell The center of the cell What is the formula for this alloy? Show how you arrived at your answer. What are the two types of alloys and which type is this structure.