1. Electronegativity

2. Electronegativity and Bond Polarity
Dipole Moments

3. Acids and Bases BrØnsted-Lowry Acids and Bases
A BrØnsted-Lowry acid is a proton donor.
A BrØnsted-Lowry base is a proton acceptor.
H+ = proton

4. Formal Charge
Used for electron ‘book-keeping’ in molecules
Sometimes atoms have different numbers of bonds
than their ‘usual’ number
FC = # of valence electrons – (# of bonds to atom +
# of nonbonding electrons)
Example: DMSO

5. Structure and Bonding Resonance
These structures are called resonance structures. A double headed arrow is used to separate the two resonance structures.
Resonance allows certain electron pairs to be delocalized over several atoms, and this delocalization adds stability

6. Structure and Bonding Drawing Resonance Structures
Rule [1]: Two resonance structures differ in the position of multiple bonds and nonbonded electrons.
Rule [2]: Two resonance structures must have the same number of unpaired electrons.
Rule [3]: Resonance structures must be valid Lewis structures.

7. Structure and Bonding Drawing Resonance Structures
Curved arrow notation shows the movement of an electron pair.

8. Structure and Bonding Resonance Hybrids
A “better” resonance structure is one that has more bonds and fewer charges.

9. Structure and Bonding
Drawing Resonance Hybrids

10. Acids and Bases Reactions of BrØnsted-Lowry Acids and Bases
A BrØnsted-Lowry acid base reaction results in the transfer of a proton from an acid to a base.
Strong acids have weak conjugate bases (and vice-versa)

11. Acids and Bases Reactions of BrØnsted-Lowry Acids and Bases
Curved arrow notation.
Equilibrium arrows.

12. Acids and Bases Acid Strength and pKa
The more readily a compound donates a proton, the stronger an acid it is.
Acidity is measured by an equilibrium constant

13. Acids and Bases Acid Strength and pKa
Various pKa values: HCl, HCN, H2O, CH3COOH, CH4

14. An acid will donate a proton to the conjugate base of a weaker acid
The conjugate base of a weaker acid will remove the proton from a stronger acid

15. Predicting if acid-base reactions will occur
Water (pKa = 15.74); acetylene (pKa = 25).
Which is the stronger acid?
Does hydroxide ion react with acetylene?
(It’s useful to identify acid, base, conj. acid, conj. base)

16. Acids and Bases Lewis Acids and Bases
A Lewis acid is an electron pair acceptor.
A Lewis base is an electron pair donor; lone pair or an electron pair in a  bond.
A BrØnsted -Lowry base always donates this electron pair to a proton, but a Lewis base donates this electron pair to anything that is electron deficient.

17. Acids and Bases Lewis Acids and Bases
Any species that is electron deficient and capable of accepting an electron pair is also a Lewis acid.
Common examples of Lewis acids: BF3 and AlCl3.

18. Acids and Bases Lewis Acids and Bases
Lewis acid-base reactions illustrate a general pattern in organic chemistry. Electron-rich species react with electron-poor species.
In the simplest Lewis acid-base reaction one bond is formed and no bonds are broken. This is illustrated in the reaction of BF3 with H2O. H2O donates an electron pair to BF3 to form a new bond.
electrophile
nucleophile

19. Acids and Bases
Lewis Acids and Bases

20. Noncovalent interactions between molecules
Dipole-Dipole Forces
Dispersion Forces

21. Hydrophilic / Hydrophobic