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Exam #3 Topics and Sample QuestionsIonic Compound Bonding and StructureSymmetry: Identifying symmetry elements and determining point groupsCoordination Chemistry: Structures and isomerismCoordination Chemistry: Bonding and spectroscopySome Questions:Ionic Compounds2714625-44451. The formula for lattice energy, Uo, is: Compare each term for the two salts: MgBr2 and KBra) Circle for which each is larger:Z+Z-MgBr2 orKBrorsameMMgBr2 orKBrorsame(1 – 1/n)MgBr2 orKBrorsameb) Which overall do you expect to have a stronger lattice energy?MgBr2 orKBrorsamec) Which term in the equation do you think is most important in any difference between them? d. What is the purpose of the Madelung constant?2. The solid spheres represent O; the hollow spheres represent Ti.What is the formula of the compound? What is the oxidation state of the Ti?3. A Bragg’s Law question: Symmetry2775585137160008. List the ALL symmetry elements and point group for each of these molecules.Rotation axesMirror planesInversion centerBrF5Point group: _____XeF4Point group: _____456247513335009. All five molecules below are planar (flat). Which two molecules have the same point groups as this transition metal compound? Circle them and note what the point group is here: _____Which structure above has the Cs symmetry point group? Draw an arrow to it.Which molecule(s) have an inversion center? Write an “i” below any that do.Transition Metal Chemistry10a. Consider the EDTA (ethylenediaminetetraacetic acid) anion, and the schematic of a coordination complex it forms. What is the coordination number of the complex? ________________What is the denticity of the EDTA ligand? Give a word or a number. The word should not include the phrase “poly.” __________________If the CH2CH2 bridge between the two N atoms was to break in the metal-bonded EDTA, the coordination number would be ______ and the denticity would be __________________.10b. Co(trien)(NH3)22+ three views: Coordination Number: _________Denticities of each ligand: __________________________11. All ions exist in aqueous solution as octahedral compounds, where the six ligands are water molecules. Consider the Cu2+ ion in water.25717505715Considering this complex, answer the following questions:What species is the Lewis acid? _____________What species is the Lewis base? _____________What is the donor? _____________What is the acceptor?_____________What is the charge on Cu?_____________What is the d-electron configuration? _____________00Considering this complex, answer the following questions:What species is the Lewis acid? _____________What species is the Lewis base? _____________What is the donor? _____________What is the acceptor?_____________What is the charge on Cu?_____________What is the d-electron configuration? _____________2505075377825a. Draw a constitutional isomer (connectivity based) of this compound. What specific kind of isomer have you drawn?b. Draw a stereoisomer (spatial based) of this compound.00a. Draw a constitutional isomer (connectivity based) of this compound. What specific kind of isomer have you drawn?b. Draw a stereoisomer (spatial based) of this compound.12. Consider the compound, Ni(NH3)4Cl(SCN). The SCN ligand can potentially bond via the S-end or the N-end.13. Another popular ligand in transition metal chemistry is terpyridine, abbreviated “trpy.” Its organic line structure is given below.2857500106680a. What is the maximum denticity of this ligand?________________b. One compound containing trpy is shown below: Ni(trpy)Cl3-. How many other isomers of this compound are possible? Explain.c. Would a similar compound that used three pyridine ligands instead of tery be more stable or less stable?7048519588500Pyridine: 54102007620d. Here is an isomer of trpy. Is it expected to behave similarly or differently than trpy? Explain in what ways it would be similar and in what ways it would differ.14a. Below is a molecular orbital diagram for a transition metal compound. Label it and explain everything you can about it. Fill in electrons if the compound were Cr(NH3)63+.14b. How many unpaired electrons will FeCl63- have? Fill in the d-orbital portion of the MO diagram to show how you get the answer.15a. The metal orbital portion of MO diagrams for two complexes of Ni2+ are shown below.a. Which has stronger metal-ligand bonding? _________b. Which will absorb light at longer wavelengths? __________15b. If Zn2+(aq) could be oxidized to Zn3+(aq) (it can’t, really, but if it could…) would it likely result in a colored aqueous solution?Recall that (aq) means the metal ion is bonded to six water ligands.Use the molecular orbital diagram to support your answer.15c. We discussed in class that the Mn2+ ion in aqueous solution is colorless, unlike almost all the other transition metal ions. If Mn2+(aq) is reacted with an oxidizing agent, the solution rapidly becomes deeply colored. Use the molecular orbital diagrams below to explain why. 15d. Explain why Re2+(aq) might be a colored solution, even though it, like Mn2+, is a d5 metal ion. 16. Determine the oxidation state and d-electron configuration on metals in coordination compounds.Fe is Fe(CN)63-Mn in Mn2(CO)917. Predict relative stability using the chelate effect, and explain it.Which is more stable: Ni(NH3)62+ or Ni(en)32+? ................
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