rm101510.pdffamilydayprogram2010-1CH301 Random Musings, October 14, 2010 1. The results from quiz 3 were very good with an average of 80%. Good for you, though I have to say that the quiz was certainly far easier than the practice quizzes and I am going to definitely be upgrading the difficulty of the next quizzes and the exam as we start to get more quantitative. (In other words, this is technically the easiest material in the entire CH301 and CH302 sequence.) I tossed one question, on the number of pi bonds in NCN-, not because the answer was incorrect, but because it offended my sensibilities in that half of you would be getting it right because you drew one triple bond and half of you could be getting it right because you drew two double bonds—note that even formal charge arguments let us down there. 2. A couple of recent e-mails to brighten my day (I love e-mails that start with, “Okay, you were right”. From a current student: Hi Dr. Laude, I know you get a lot of these every day from kids like me asking for help, but here is another one. I feel like I have been trying and studying a lot for this class lately by doing the worksheets, going to TA sessions to answer questions I do not understand, and doing the practice quizzes and tests in order to prepare but I am still having problems. For example, in preparing for Quiz #3 tomorrow, I feel as though I know the information (I memorized the question types and I suppose I thought I knew the recipes for answering them) but when it came time to take the practice quizzes it became apparent that I didn't understand it. I went to the Learning Center today for help, which did help a little and I have a study group I am going to tonight, so I hope that will help me clear things up. Anyway, I guess I just wanted to let you know, I really do care about how I do in this class and I want to do well, so if there is any further advice you can offer me, please, please do. Thank you xxxxxxxxx Dear xxxxxx Trust in the process. You are beating yourself up and you haven't even done badly yet. The practice quizzes are a lot harder than the regular quiz, for one thing. After you take the quiz, e-mail me with the score you received and we can talk about what to do next, and if we need to meet, we can. Best, Dave Laude Hi Dr. Laude, Thank you!Okay, so you were right. (Surprise!) Thank you so much for responding and for the encouragement. I did do well on my quiz, thank goodness; I got a 100--WHOOOOOO!!! So I suppose now I have a better idea of how to study for the future. If I have any more questions or concerns I will be sure to either ask you at a discussion session or via email. Best wishes, xxxxxxxx From a former student Dr. Laude, I don't know if you remember me or not, but I took your chemistry class my freshman year, both semesters. I'm currently taking Organic with Dr. Iverson and we recently took our first test. I just wanted to write to you and tell you how much I appreciate your class and how you taught it even though it was really tough for me at first. On my first organic test I got a 92. I am so happy and I attribute a lot of my success to you. If you hadn't taken the time out to meet with me in your office and personally go over my study skills, I don't think I would have gotten the grade I got. I also appreciate you incorporating organics at the end of CH302. If almost killed my grade in your class, but I got through it and am now doing well in organic because of it. Thanks you so much again.So look, persevere. You can change your performance in this class, but you have to want it. Taking the final for everything doesn’t mean you can coast till then, it means starting right now to change, and by the time the exam comes, you are ready to shine. 3. I have posted the video of my Sunday 7pm “How to get an A” and you can find notes on it in the musings. 4. There is a quiz coming soon (next, Thursday) and like clockwork one week early, here are the 8 question types on the next quiz 4. Note that practice quizzes will be posted this weekend along with worksheet 8 on MO theory and worksheet 9 on gases: • Determining bond order for a homonuclear diatomic molecule or ion (worksheet 8) • Determining paramagnetism for a homonuclear diatomic molecule or ion (worksheet 8) • Ranking bond energy or length based on bond order (worksheet 8) • Identifying delocalization in a molecule (worksheet 8) • Ideal gas law calculation for a chemical reaction involving gases (worksheet 9) • Ideal gas law calculation involving a state change in a gas system (worksheet 9) • Kinetic Molecular Theory explains gas speed, diffusion or effusion (worksheet 9) • Ranking non-ideality in gases (worksheet 9) 5. Definition corner: Here is some vocabulary to reinforce what you know as you put all the concepts about bonding together: • Electronic geometry refers to the shapes of the electron rich regions. So erase the atoms and just look at the electron pairs and the five possible answers. • Molecular geometry refers to the13 possible shapes of the atoms in the molecule and ignores the electrons. So erase the electrons and just look at the shape the atoms take on. If you see a question that states: what is the shape of H2O, for example, they want to know the shape of the molecule and the answer is “angular.” It is these shapes that exhibit the level of symmetry that explains whether a molecule is polar or not. • Dipole moment: a vector describing the orientation of electron density. In this class the DEN is the dipole moment. • Ionic bond: ΔEN >1.5 Example: Na—Cl • Covalent bond: ΔEN <1.5 Example: C—O • Polar bond: ΔEN > 0 Example, Na—Cl or C—O • Non-polar bond: ΔEN = 0 Example, Br—Br or C—C • Polar molecule (asymmetry): ΣΔEN > 0 Example, H2O or CHCl3 • Non-polar molecule (symmetry): ΣΔEN = 0 Example, Br—Br or CCl4 • AOs are atomic orbits. Two AOs are need to make an MO and AOs are made from individual or combinations (hybrids) of s, p, d orbits • MOs are molecular orbits (which is a fancy way of saying bonds) and take an electron from two AOs to make either a s or p bond. • Resonance suggests that there are multiple identical Lewis structures that can be drawn when you have left over p bonds and too many locations on a molecule to put
View Full Document
Unlocking...