233HExam2

Midterm Exam 2

Coverage: Chapters 23, 24, 26, 27 and MO theory from Chapter 11 as it applies to organic compounds

Please note that these chapters are far more detailed than I believe is warranted at this stage of your career--most of you will learn this material in depth next year when you take a full-year Organic Chemistry course. Here I list the sections that I have emphasized and the material you need to master for the exam.

Chapter 11 (review):

11-1: Understand what bonding theories attempt to do: predict structure, estimate energies (both of the molecule as a whole, and of electrons in the molecule), and provide a quantitative relationship between the two.
11-2, 11-3: The localized valence bond method introduces the concept of mathematically mixed atomic orbitals providing stabilization for an electron pair shared between two atoms. Use of hybrid atomic orbitals to explain geometry of bonding/lone pairs of electrons.
11-5: Molecular orbital theory applies this across all atoms and leads to a delocalized bonding model. Comparison of VB and MO pictures for methane, ethylene, acetylene.
11-6: Benzene and other "resonance-stabilized" molecules

Chapter 23: Sections 1, 2 for heavy focus; I expect you to have read Sections 3-7.

Chapter 24: Sections 1, 2, 4, 5, 6, 7. Sections 8 and 9 are direct extensions of prior work and I will assume you can implement the concepts.

Chapter 26:

Section 26-1: constitutional (or structural) isomerism, naming alkanes (up to C₁₀) and alkyl groups; recognizing functional groups. Know Table 26.2. Using bond-line structural depictions of molecules.
Bonding: Review Sections 11-2, 11-3, 11-4, 11-5 and 11-6 if you need refreshing from CH 231H (see above).
Section 26-2: free rotation about C-C single bonds. Petroleum as a source of alkanes. General molecular formula: C_nH_2n+2.
Section 26-3: Cycloalkanes: recognize cyclic structures; molecular formula subtracts 2 hydrogens per ring. You are not responsible for analyzing conformations of cyclohexane.
Section 26-4: recognize chiral and achiral objects (molecules), and identify stereocenters. Draw mirror images of molecules and redraw them after rotation in space.
Section 26-5: Restricted rotation about C=C double bonds, and the distinction between sigma and pi bonds. Cis/trans isomers. You are not responsible for the more complex E/Z nomenclature.
Section 26-7: Recognize and be able to draw resonance structures for benzene and other aromatic rings.
26-7: Recognize functional groups and understand their impact on polarity (and thereby water-solubility and boiling point), and the acid or base properties of specific groups.

Here is the Exam Key from 2016 for sample questions.

Links to the exam and exam key

High: 98

Average: 87

Scores above the average can be regarded as A or A-; scores below the average are B+ or B.