1. Chapter 1 – Bonding
Atoms trying to attain the stable configuration of a noble (inert) gas - often referred to as the octet rule
1.2 Ionic Bonding - Electrons Transferred
1.3 Covalent Bonding - Electrons Shared
type of bond that is formed is dictated by the
relative electronegativities of the elements involved

2. the attraction of an atom for electrons
Electronegativity
the attraction of an atom for electrons

3. Important Electronegativity ValuesH
2.1
Li Be B C N O F Cl
3.0 Br
2.8 I
2.5

4. Important Electronegativity ValuesH
2.1
Li Be B C N O F Cl
3.0 Br
2.8 I
2.5

5. Electrons Transferred
1.2 Ionic bonding
Electrons Transferred
Big differences in E.N. values
Metals reacting with non-metals

6. H . + H . H : H 1.3 Covalent Bonding - Similar electronegativities
Lewis dot representations of molecules
H H .
H : H
B.D.E
Hydrogen atoms
Hydrogen molecule
+104 kcal/mol
B.D.E
+104 kcal/mol
B.D.E. = bond dissociation energy

7. 1.3 Lewis Dot Structures of Molecules

8. 1.4 Double bonds and triple bonds
Double bonds - alkenes
Triple bonds - alkynes

9. 1.5 Polar covalent bonds and electronegativity
H2 HF H2O
CH4 CH3Cl
Based on electronegativity F : .. H   - + H Li

10. 1.6 Structural Formula in Organic Chemistry

11. 1.6 Constitutional Isomers
Same molecular formula, completely different chemical and physical properties

12. 1.7 Formal Charge
Formal charge = group number
- number of bonds
- number of unshared electrons

13. 1.8 Resonance Structures - Electron Delocalization
Table 1.6 – formal rules for resonance

14. 1.9 Shapes of Molecules
Shapes of molecules are predicted using VSEPR theory

15. 1.9 Shape of a molecule in terms of its atoms
Figure 1.9
Table 1.7 – VSEPR and molecular geometry

17. Trigonal planar geometry of bonds to carbon in H2C=O
Linear geometry of carbon dioxide

18. 1.10 Molecular dipole moments
Figure 1.7

19. 1.11 Curved Arrows – Extremely Important
Curved arrows are used to track the flow of
electrons in chemical reactions.
Consider the reaction shown below which shows
the dissociation of AB:

20. Curved Arrows to Describe a Reaction
Many reactions involve both bond breaking
and bond formation. More than one arrow
may be required.

21. 1.12 Acids and Bases - Definitions
Arrhenius
An acid ionizes in water to give protons. A base ionizes in water to give hydroxide ions.
Brønsted-Lowry
An acid is a proton donor. A base is a proton acceptor.
Lewis
An acid is an electron pair acceptor. A base is an electron pair donor.

22. 1.13 A Brønsted-Lowry Acid-Base Reaction
A proton is transferred from the acid to the base. + . . – . + B + H A B H A
base
acid
conjugate acid
conjugate base

23. Proton Transfer from HBr to Water
hydronium ion (H3O+) H H .. + .. – . . . . . . . . O O H + H Br + Br .. .. H H
base acid conjugate conjugate acid base

24. Equilibrium Constant for Proton TransferH . H . .. Br – . .. . . + . + H Br O + O H ..
[H3O+][Br–]
Ka =
[HBr]
pKa = – log10 Ka

25. Acids and Bases: Arrow Pushing
[H3O+][Br–]
Ka =
~ 106 for HBr, pKa = - 5.8
[HBr]

28. Need to know by next class:
pKa = -log10Ka
STRONG ACID = LOW pKa WEAK ACID = HIGH pKa
HI, HCl, HNO3, H3PO4 pKa -10 to -5 Super strong acids
H3O+ pKa – 1.7
RCO2H pKa ~ 5 acids
PhOH pKa ~ 10 get
H2O, ROH pKa ~ 16 weaker
RCCH (alkynes) pKa ~ 26
RNH2 pKa ~ 36 Extremely weak acid
RCH3 pKa ~ 60 Not acidic at all

29. Essentially not acidic
1.14 What happened to pKb?
A separate “basicity constant” Kb is not necessary.
Because of the conjugate relationships in the Brønsted-Lowry approach, we can examine acid-base reactions by relying exclusively on pKa values.
pKa ~60
Essentially not acidic
Corresponding base
Extremely strong

30. 1.15 How Structure Affects Acid/Base Strength
Bond Strength
Acidity of HX increases (HI>HBr>HCl>HF) down the periodic table as H-X bond strength decreases and conjugate base (X:- anion) size increases (basic strength of anion decreases). HF
HCl
HBr HI
pKa
3.1
-3.9
-5.8
-10.4
weakest acid
strongest acid
strongest H—X bond
weakest H—X bond

31. CH4 NH3 H2O HF pKa 60 36 16 3.1 weakest acid strongest acid
Electronegativity
Acidity increases across periodic table as the atom attached to H gets more electronegative (HF>H2O>H2N>CH4).
CH4
NH3
H2O HF
pKa 60 36 16
3.1
weakest acid
strongest acid
least electronegative
most electronegative

32. O – H bond in CF3CH2OH is more polarized
Inductive Effects
Electronegative groups/atoms remote from the acidic H can effect the pKa of the acid.
pKa = pKa = 11.3
O – H bond in CF3CH2OH is more polarized
CF3CH2O- is stabilized by EW fluorine atoms

33. pKa ~16 pKa ~5 Resonance Stabilization in Anion
Delocalization of charge in anion (resonance) makes the anion more stable and thus the conjugate acid more acidic
e.g. (CH3CO2H > CH3CH2OH).
pKa ~16
pKa ~5

34. 1.16 Acid-base reactions - equilibria
The equilibrium will lie to the side of the
weaker conjugate base

35. 1.17 Lewis acids and Lewis basesO
CH2CH3
• • – +
F3B O
CH2CH3
• •
F3B +
Lewis acid
Lewis base
Product is a stable substance. It is a liquid with a boiling point of 126°C. Of the two reactants, BF3 is a gas and CH3CH2OCH2CH3 has a boiling point of 34°C.