2 (27) 3 (26) 4 (21) 5 (18) 6 (8) Total (200) Periodic Table

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1 Chem 3311 Sammakia Fall 2009 Midterm 1 Student ID page points: 2 (27) 3 (26) 4 (21) 5 (18) 6 (8) Total (200) Periodic Table e Li Be B C N O F Ne Na Mg Al Si P S Cl Ar K Ca Sc Ti V Cr Mn Fe Co Ni Cu Zn Ga Ge As Se Br Kr Rb Sr Y Zr Nb Mo Tc Ru Rh Pd Ag Cd In Sn Sb Te I Xe Cs Ba La a Ta W Re Os Ir Pt Au g Tl Pb Bi Po At Rn Fr Ra Ac carbocation Wherein lies your mystery? I cannot solve it!

2 1 A) For the four molecules shown below, provide the formal charge for any charged atoms - indicate the charge and draw an arrow to the atom that bears the charge. All electrons are shown. 12 pts, -2 for each wrong answer. C N C.. 3 C B C 3 C 3 Formal Charge B) Is each molecule better described as Lewis Acid, Bronsted Acid, or base? Provide your answer on the lines above. 2) Fill in the following table. 6 pts, -2 for each wrong answer. Cl pka N 3 2 O C 3 CO 2 N O + 3 A) Draw the most important resonance structure for the molecule shown below. Show all arrows required to go from one resonance structure to the other (BOT structures should have arrows). 6 pts B) For the molecule shown in 3A above, how much positive charge resides on each carbon (C1, C2, and C3, give your answer in percentage positive charge on each carbon)? 3 points b) percent + charge on C1 percent + charge on C2 percent + charge on C3 Page 2 of 6

3 4) The alcohol shown below can be synthesized from three different alkenes. Provide two syntheses below. DO NOT PROVIDE TREE, ONLY TWO! Include the reagents required to accomplish your synthesis. 20 points total A) O B) O 5) What is the energy of each of the conformations of butane shown below. 6 pts, -2 for each wrong answer. Page 3 of 6

4 6) The reaction shown below provides three products in unequal amounts. The three products are formed from a common intermediate. Draw the mechanism for the formation of these products in the space provided below (might require more than one step from the intermediate). Be sure to include all arrows and all charges. 18 points B Br Br Br A C Br Which of these products would you expect to be formed in the smallest amount, A, B, or C? 3 points Page 4 of 6

5 7) Draw the molecular orbital diagram of - and -F. Be sure to pay attention to the starting energies of your atoms, and to the energy of the resulting orbitals. 15 points - -F 8) Define an antibonding orbital in one sentence. I m looking for the right buzz words (in the right context), and once you write the correct answer, writing more will only give you a chance to write something that is wrong. So, no more than one sentence, please. 3 points Page 5 of 6

6 Rank each group with a bracket as priority 1 or 2 according to the CIP nomenclature system. 3 points, -2 for each wrong answer Are the following pairs of molecules resonance structures, isomers, identical molecules that are drawn differently, or none of the above? 5 points, -2 for each wrong answer. O O N N O O 3 C C C + C 3 Page 6 of 6

7 below Rank each set of molecules shown below with respect to their acidity (1=most acidic, 3=least acidic) (1=most acidic, 3=least acidic) Rank the molecules shown below with respect to their acidity (1=most acidic, 3=least acidic) Rank the molecules shown below with respect to their acidity (1=most acidic, 3=least acidic) Rank the molecules shown below with respect to their acidity (1=most acidic, 3=least acidic) Draw a resonance structure for the molecule shown below and indicate if the resonance structure you drew is an equal contributor or if it is a more important contributor or a less important contributor to the true structure of the molecule. Explain your choice in ONE sentence. We re looking for the right buzz word, once you write it, writing more will only give you a chance to write something that is wrong. Draw a resonance structure for the molecule shown below and indicate if the resonance structure you drew is an equal contributor or if it is a more important contributor or a less important contributor to the true structure of the molecule. Draw the energy diagram for the rotation of butane E/Z nomenclature MO draw sigma and sigma star draw simple diagram with - -O -F Reactions simple hydration of ethylene ch two rearrangements Page 7 of 6

8 Draw a resonance structure for the molecule shown below. Show all arrows required to go from one resonance structure to the other. ow much positive charge resides on each carbon (C1, C2, and C3, give your answer in percentage positive charge on each carbon). What is the equilibrium constant for the following reaction? Ethane thiol + hydroxide Fill in the following table: Cl pka N3 2O C3CO2 N4+ 3O+ Page 8 of 6