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: 5. Delocalization of charge over a larger area is stabilizing. 8. Reactions will occur if the products are more stable than the reactants (motive) and the energy barrier is low enough (opportunity).

1. For acids that deprotonate to give an anion conjugate base, the stronger acid will produce the more stable anion conjugate base. In other words, when analyzing relative acid strength, compare the relative stabilities of the anion conjugate bases.

2. Use five rules when determining relative stabilities of anions (i.e. when you are predicting relative acid strength) These five rules are actually application of the following two principles: 1) negative charge is neutralized by nuclear positive charge and 2) delocalizing negative charge over a larger area is stabilizing.

a) Across a row of the Periodic Table, negative charge on a more electronegative atom is more stable. (Principle 1)

b) Down a column of the Periodic Table, larger anions are more stable than smaller ones. (This is more confusing than you think, so make sure you understand it). (Principle 2 dominates here)

c) Hybridization: The more S orbital character of the hybridization on the atom that has the negative charge, the more stable the anion (stability of anions is in the order sp>sp2>sp3) Principle 1)

d) Charges distributed over more atoms are better. (Nature hates isolated charges, so delocalizing a charge around by resonance is very stabilizing) (Pinciple 2)

e) Inductive Effect: Electronegative atoms such as F on atoms adjacent to the atom(s) with the negative charge will pull some of the charge away, thus spreading it out and leading to stabilization. (Principle 1 and 2)

3. To say it in a new way, in an acid-base reaction, equilibrium favors the side opposite that with the stronger acid, meaning the side with the more stable anion is favored.

5. In buffered aqueous solution, an acid will be present predominantly in its deprotonated state if the pH of the solution is a larger value than the pKa of the acid. If you are interested in this derivation click here

6. Protons move very fast compared to other species, so fast that equilibrium in acid base reactions occurs generally before any other kinds of reactions can take place.

7.A Lewis acid is any molecule or ion that can accept a pair of electrons to make a new covalent bond, and a Lewis base is any molecule or ion that can donate a pair of electrons (lone pair or pi bond) to make a new covalent bond. (Note these definitions include proton transfer reactions in which the proton is the Lewis acid).

9. When a Lewis acid and Lewis base combine, the product is referred to as a Lewis acid-Lewis base complex. The bond is referred to as a "coordinate covalent bond" or "dative bond".

10. Alkenes have one sigma bond and one pi bond, The reactivity of alkenes is based on the pi bond. Click here for a picture that helps you remember pi bonds.

11. The most important consequences of the pi bond are that A) the double bond cannot rotate and B) electron density is above and below the bond axis.

12. Stereoisomers of alkenes with a single substituent on each carbon atom of the double bond are named as "cis" (same side) or "trans" (opposite side).

13. Use the "E-Z" nomenclature for naming complex alkenes. Remember that "Z" means "Zame Zide". When establishing priority for for E vs. Z, it is the same as for R and S. Higher atomic number wins and count multiple bonds as being equivalent to that same number of bonds to the atoms taking part.

HOMEWORK:

Read: Sections 4.1-4.7 in the eBook.

There are no Quizzes or Homeworks while the TA's grade the exams.

Here is your second and final Breakout Learning session.  After reading the short handout on organic reaction mechanisms you access by clicking here, click on the link called "Breakout Learning" on the Canvas page margin and follow the directions. You will need to complete the Reaction Mechanisms assignment by next Tuesday evening (Sept. 29) at 10 PM. Note you do not have any homework due next Wednesday while the TAs grade the exam, so this is all you will need to do for this class in the next several days!   Just like last time, the successful completion of the Breakout Learning discussion will earn you 0.5 T Score or raw percentage points on the 2nd midterm. But my bet is it will help you earn far more "real" points than that on the two upcoming midterms and even the final itself because you will understand reaction