Saturday, September 24, 2011

About That "A" In Ochem

How does one actually do this?

I know, work the problems, play with my molecule set (rearrange chair structures into boat so I can see how the H atoms arrange axial v. equitorial?)

Ahhh yes.  I may get there.  First I have to memorize the pKa required molecules, and all the functional groups assigned.  The pKa might be DMSO or H2O... lucky me.

Found the easiest way is obviously note cards but then found that memorizing the functional groups along with the pKa helpful as well.  If the carbon is triple bonded to a nitrogen, the pKa = xxx and the group is a cyano (I think).

Anyway, exam in a week.  A bit stressed but nothing out of the ordinary.  I will get an "A"... I will.  I will.  I will.

6 comments:

Solitary Diner said...

Practice, practice, practice. There is no way around it in organic chemistry. Learning the fundamental principles and the patterns of reactions is also very helpful, as it makes it much easier to remember the vast amounts of information. Good luck.

Adam Browning said...

The "trick" that my orgo prof focused on was to "always know where your electrons are". Focusing on electronegativity and electron density was a lot easier than trying to memorize pKa's and individual reactions. e.g. an oxygen pulling electron density from a carbon makes the hydrogens on the C more acidic.

Best of luck on your exam!

medschoolodyssey said...

A lot of how you succeed in organic chem is dependent upon your professor and how they teach the class. My professor focused on mechanism and understanding, so it wasn't all that difficult. I worked most of the problems in the textbook, used email and office hours to get questions answered that came up, and then went and took the exams.

Again, my professor specifically focused upon the reasons why things happened or were a certain way, rather than having us memorize a bunch of facts. A lot of the topics that were in my section wouldn't have made sense to memorize anyway. We covered orbitals, resonance, isomers, stereoisomers, nomenclature, conformations, NMR, acid/base chemistry, and kinetics before we touched reactions of any kind. Even the acid/base stuff was really just an exercise in determining charge stability. The last 6 weeks of the semester, we did substitution, elimination, and addition reactions.

Not all professors teach the subject that way. I have a friend that's taking a different section of organic chemistry and after helping her for a few weeks, I now see why so many people think that organic chemistry is nothing but memorization. Her professor didn't introduce nomenclature, structures, or anything which is covered in the first 5 chapters of her book. The first day, he started by introducing Grignard reactions and has basically done nothing but introduce a series of reactions all semester. The level of her class is essentially memorization of those reactions and then regurgitating them on exams by synthesizing new molecules using those reactions.

If your class is taught like the former, than count your blessings. If it's the latter, then you have my sympathies. I could not learn organic chemistry that way. The most frustrating thing about learning that way is that very few people are able to help you. I helped her review for her first exam and it was really difficult - she hasn't learned line drawings or nomenclature yet, so communication is really hard. Also, explaining reaction chemistry to her is hard when she has never heard of nucleophiles, resonance, substitution, or anything of the sort.

Hopefully, your class isn't like that.

A Doc 2 Be said...

@ Adam - for the most part, right now, we're being asked to memorize 28 pka's, and about 20 functional groups. The pkas are in both DMSO and H2O where feasible; also we need to know which H is the most acidic... in the long run that will probably help as we start moving electrons with a catalyst... I'm using the functional groups as a help as I memorize those; simultaneous but not quite.

@ MSO - my ochem professor is rated very highly - he sees his job as a coach; we started with basic Lewis structures along with formal charge, then built isomers and resonance structures, then built into acid/base, and finally into gauche/anit structures. We just completed an in-class on chair structures which I get to s certain extent (after trying to figure it out while falling asleep, I dreamed the resolution)... anyway, I think I have it and if I play with the actual model kit, I bet I'll just "know" which H are axial and which are equitorial. Right now, I'm a little confused on how to draw them...

We've likewise spent a considerable amount of time on sp3, sp2, sp... and hybridization which I finally get!! Yeay me. After 7 straight hours sitting in a chair in the library (yeay for Concerta!), I finished the 100 problems, with 4 sub-components per problem, tonight - for the first chapter! I feel sooooo behind.

Sounds like I got a professor like yours and is a blessing... in many aspects - he actually wants his students to succeed; even premeds!

I "took" one of his former exams tonight while studying. Got a 96/100... Does not mean I'll quit doing the homework problems or quit studying, just means I'll continue to amp the pressure on me to "get" that 96 on the actual exam.

What a "A" in ochem would do for my applications!! :)

medschoolodyssey said...

Sounds like you're prof is one of the good guys. Spend a lot of time on resonance, orbital hybridization, and molecular orbitals - the bulk of organic chemistry is explained by those three topics.

The topics in organic chemistry seem hard because it's the first class that really pulls back the curtain and shows you what is actually going at the molecular level. Electrons are not point particles, nor do they orbit the nucleus or reside in nice, well-defined orbital hybrids. You're being introduced to a very profound idea and skipping over a lot of things in between - perhaps that is why it feels so alien at first. There are a tremendous number of "lies" that are being corrected.

Glad to hear you have a good professor and based on your performance on the practice exam, I think you'll do just fine.

But, not to burst your bubble, even with an A in both semesters of organic chemistry, you will still feel like your application is less than acceptable and that you are a less-than-stellar applicant. I certainly do.

A Doc 2 Be said...

@MSO

I never feel like I'm a great candidate; in fact most days, I wonder why I'm trying to do the unthinkable at this age with my u-grad GPA from 30 years ago.

My focus is on today, and not what I cannot fix. What happens, happens...

I'm just hoping to be given a chance!