Rules of the Day
Click here for a copy of my lecture notes from today's lecture
Click here for a copy of the handout used in class today
Featured Golden Rules of Chemistry: 3. There are two possible arrangements of four different groups around a tetrahedral atom. The two different arrangements are mirror images of each other, a property referred to as chirality and often compared to handedness.
1. When converting a flat cyclohexane representation (wedges and dashes) or a Haworth projection to identify the more stable three-dimensional chair structure draw both, remembering that UP is UP and DOWN is DOWN and that the more stable chair has more large groups equatorial.
2. Look at the web handout on stereochemistry (click here for a copy) to help with definitions
3. Chiral objects (or molecules) cannot be superimposed upon their mirror image.
4. An object or molecule is not chiral if it contains a plane of symmetry or a center of symmetry.
5. An enantiomer is any molecule that cannot be superimposed on its mirror image (it does not have a plane or center of symmetry).
6. Diastereomers are molecules that are stereoisomers but not enantiomers; a situation that arises when there are more than one chiral center in the same molecule.7. Tetrahedral atoms such as carbon with four different substituents are chiral and are called chiral centers.
8. Name enantiomers as R or S by assigning Cahn-Ingold-Prelog "priority" to each atom attached to the stereocenter (higher atomic number AT THE FIRST POINT OF DIFFERENCE and watch those multiple bonds!), then arrange the molecule so you are looking down the chrial center-lowest priority bond. Count around the ring; clockwise is "R" and counterclockwise is "S".
9. Look at the handout on stereochemistry (click here for a copy) to help with definitions.
10. If there are "n" chiral centers in a molecule, there are 2 to the "nth" power possible stereoisomers, although symmetry can make this number lower (see "meso"). For a molecule with 2 chiral centers, that means 4 possible stereoisomers, for 3 chiral centers that means 8 possible stereoisomers, etc.
HOMEWORK:
Read: Sections 3.1 - 3.7 in the ebook textbook. This text is part of the Longhorn Textbook access program.
After reading sections 3.1 - 3.7, click on the link called "Breakout Learning" on the Canvas page margin and follow the directions. You will need to complete the assignment by this coming Sunday evening (Sept. 20) at 10 PM. You have the entire week! And this is going to prepare you for the hardest subject we will encounter so you all crush it! Succesful completion of the Breakout Learning discussion will earn you 0.5 TScore or raw percenbtage points on next week's midterm. But my bet is it will help you earn far more "real" points than that on the midterm itself because you will understand stereochemistry! Click here for the Breakout Learning Step by Step onboarding guide. In addition, here is a 1-min video of the student experience. Alternatively, this 4-min best practices video shows students all of the steps in the onboarding guide and gives them a sense of how to get the most out of their Breakout discussion.
Take the Daily Quiz 7 before 10 PM tomorrow. Click here to access the quiz. These quizzes are designed to review the important material from today's lecture. Together, they will count as 3% of your final grade.
Finish working on the Homework Problem Set 3, due at 10 PM tonight Wednesday, September 16. Note there are Aktiv Learning and Gradescope Questions, and you MUST DO BOTH. Click here to access to the Aktiv Learning electronic homework system.
Click here to access Aktiv learning Homework Problem Set 3
Click here to access Gradescope Homework Problem Set 3
Start working on the Homework Problem Set 4, due at 10 PM on Wednesday, September 23. Note there are Aktiv Learning and Gradescope Questions, and you MUST DO BOTH. Click here to access to the Aktiv Learning electronic homework system.
Click here to access Aktiv learning Homework Problem Set 4
Click here to access Gradescope Homework Problem Set 4
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