Outline for Today Monday, Nov. 19 Chapter 9: Theories of Bonding - PowerPoint PPT Presentation

Outline for Today Monday, Nov. 19 • Chapter 9: Theories of Bonding • Molecular Orbitals of P-Block Elements • Chapter 9 Integrative Example Problems � 1

Making Molecular Orbitals σ * (sigma-star) Antibonding orbital σ (sigma) Bonding orbital

Putting Electrons in Orbitals H 2 Lowest Unoccupied Molecular Orbital (LUMO) Highest Occupied Molecular Orbital (HOMO) Stable Molecule! Stable Molecule!

Molecular Orbitals for Diatomics Made from the P-Block Elements 1. Starting Atomic Orbitals Draw the right number of boxes (1 for each subshell) Put them in order of increasing energy. Label the atomic orbitals 2. Mix the atomic orbitals. For Diatomics: A.O. mix if they are the same shape, l , and have the same angular momentum, m l 3. Draw and label boxes for molecular orbitals. Remember conservation of orbitals! Bonding orbitals are lower in energy http://www.chemeddl.org/resources/models360/ than anti-bonding orbitals models.php?pubchem=14774

Molecular Orbital Practice Problems • Draw the molecular orbital diagram for: • Li 2 • O 2 • O 22-

Molecular Orbital Practice Problems • Draw the molecular orbital diagram for: • Li 2 • O 2 • NO • What is the bond order for each molecule? • How many electrons are in π bonds in each molecule? • Is it Paramagnetic or Diamagnetic?

Molecular Orbital Diagram for O 2 LUMO HOMO Paramagnetic! para (greek)= attached Unpaired electrons means it will stick to the magnetic!

MO for Diatomics Made from the P-Block Elements

Molecular Orbitals for Diatomics Made from the P-Block Elements O 2 , F 2 , Ne 2 B 2 , C 2 , N 2

MO for Diatomics Made from the P-Block Elements

3D molecular Geometry • Based on VSEPR theory and hybrid orbital theory, predict the 3D structure and hybridization of: 1. XeF 4 2. ClF 3 3. SF 4 • In one sentence explain WHY you placed the lone pairs where you did. https://chem.libretexts.org/Ancillary_Materials/Visualizations_and_Simulations/ PhET_Simulations/PhET%3A_Molecule_Shapes

Visualizing multiple π Bonds • Using at least TWO sketches, draw the π bonds of carbon monoxide.

Visualizing multiple π bonds • http://www.chemeddl.org/resources/models360/models.php?pubchem=281

Visualizing π bonds • Sketch a picture of CO 2 to illustrate where the π bonds are in this molecule. • According to Hybrid Orbital Theory, why are the two π bonds perpendicular to each other? http://www.chemeddl.org/resources/models360/models.php?pubchem=280

Comparing π bonds of Hybrid Orbital Theory and Molecular Orbital Theory • Below are the two π bonds predicted by MO theory. How are they similar and how are they di ff erent from those predicted by hybrid orbital theory?

What’s the most likely isomer structure? • What is the best lewis structure of N 2 O? • What is the best lewis structure for SCN - ?

What’s the difference between isomer structures and resonance structures? O O H C C H C - H H C H H H H O - O C C H H C H C H H H Identify the two ISOMERS and the two RESONANCE structures

Drawing Isomers and Resonance Structures • Complete the Lewis structure of the following neutral molecule O C F F N F • Draw an isomer of CNOF 3

Draw the resonance structures of PO 43- • What is the average bond order of the P-O bonds? • How many σ bonds are in each structure? • How many π bonds are in each structure? • How many unhybridized p orbitals remain on the central atom?