Transcript Slide 1

Chemistry 177
November 2, 2009
Take out CLICKERS:
“GO 41 GO” -or- “CH 41 CH”
NEXT LECTURE:
Monday, Nov. 2; Bring CLICKERS
READ BLBM, Chapter 8.5-8.8
HOMEWORK #11:
Ch. 8: # 46, 48, 50; Ch. 9: # 61, 62, 66
(Due in Recitation Thursday, November 5)
Chapter 8: Basic Concepts of Chemical Bonding
Molecular Orbital Energy Diagrams: Types of Orbital Overlap
Energy
F2
Chapter 8: Basic Concepts of Chemical Bonding
Possible Clicker Questions
Chapter 8: Basic Concepts of Chemical Bonding
Molecular Orbitals: Distance Effects -- Halogens
*2p
Energy
*3p
UV
 < 400 nm
*4p
551 nm
*2p
*5p
650 nm
*3p
*4p
730 nm
*5p
Energy of np AOs
2p
3p
4p
5p
4p
3p
2p
5p
5p
4p
3p
2p
F2
(Colorless)
144 pm
Cl2
(Yellow-Green)
192 pm
Br2
(Red-Brown)
228 pm
I2
(Violet)
266 pm
Chapter 8: Basic Concepts of Chemical Bonding
Molecular Geometry: Lewis Structures and Molecular Orbitals
Energy
*2p
*2p
2p
2p
*2s
2s
Chapter 8: Basic Concepts of Chemical Bonding
Molecular Geometry: Lewis Structures
Value:
(a) Identify geometrical features: bond distances, bond angles;
(b) Locate regions of chemical reactivity;
(c) Identify bonding features creating special stability.
(1) Use Lewis-Dot Structures for Main-Group Elements
H
Li
Be
B
C
N
O
F
(2) Octet Rule:
(3) Electron pairs are either bond pairs or lone pairs.
He
1s
Ne
2s, 2p
Chapter 8: Basic Concepts of Chemical Bonding
Molecular Orbitals: Electronegativity Effects – Ionic/Covalent
Rules:
(a) AO on more EN atom contributes more to bonding MO;
(b) AO on less EN atom contributes more to antibonding MO
(Pauling ENs: F = 4.0, Cs = 0.7)
ENERGY
ENERGY
ENERGY
Chapter 8: Basic Concepts of Chemical Bonding
Molecular Geometry: Lewis Structures (Rules)
(a) Create a
(b) Count total number of
(c) Draw a
(d) Complete the
Utilize
(e) Calculate
Chapter 8: Basic Concepts of Chemical Bonding
Molecular Geometry: Lewis Structures (Examples)
Hydrogen Fluoride: HF
Chapter 8: Basic Concepts of Chemical Bonding
Molecular Geometry: Lewis Structures (Examples)
Ammonia: NH3
Chapter 8: Basic Concepts of Chemical Bonding
Possible Clicker Questions
Chapter 8: Basic Concepts of Chemical Bonding
Molecular Geometry: Lewis Structures (Examples)
Methane: CH4
Ethane: C2H6
Propane: C3H8