Bonding/Lewis Dots Lecture Page 1 of 12 Date. Bonding. What is Coulomb's Law? Energy Profile: Covalent Bonds. Electronegativity and Linus Pauling

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1 Bonding/Lewis Dots Lecture Page 1 of 12 Date Bonding What is Coulomb's Law? Energy Profile: Covalent Bonds Electronegativity and Linus Pauling 2.1 H 1.0 Li 0.9 Na 0.8 K 0.8 Rb 0.7 Cs 0.7 Fr 1.5 Be 1.2 Mg 1.0 Ca 1.0 Sr 0.9 Ba 0.9 Ra 1.3 Sc 1.2 Y 1.5 Ti 1.4 Zr 1.3 Hf 1.6 V 1.6 Nb 1.5 Ta 1.6 Cr Mo 1.7 W 1.5 Mn Tc Re Fe Ru Os Co Rh Ir Ni Pd Pt Cu Ag 2.4 Au 1.6 Zn 1.7 Cd Hg 2.0 B 1.5 Al 1.6 Ga 1.7 In Tl 2.5 C Si Ge Sn Pb 3.0 N 2.1 P 2.0 As Sb Bi 3.5 O 2.5 S 2.4 Se 2.1 Te 2.0 Po 4.0 F 3.0 Cl 2.8 Br 2.5 I At Unequal Sharing Polar Covalent Bond Coordinate Covalent Bond

2 Bonding/Lewis Dots Lecture Page 2 of 12 Date Ionic Bond How can you theoretically determine what type of bond is forming? F 2 H 2 O HCl KCl CH 4 NO 2 Lewis Structures Valence electrons Straight Forward Structures H 2 Cl 2 H 2 O CH 4 I 2 NH 3 C 2 H 6 CCl 4 PCl 3

3 Bonding/Lewis Dots Lecture Page 3 of 12 Date Structures Containing Multiple Bonds O 2 C 2 H 4 CO 2 N 2 C 2 H 2 CO HCN C 2 Cl 4 COCl 2 Complex Shapes/ Different Rules/ Ring Structures PCl 5 XeF 2 SF 4 I 3 BeH 2 PBr 5 SF 6 BF 3 C 6 H 6

4 Bonding/Lewis Dots Lecture Page 4 of 12 Date VSEPR Type Picture Shape Example Type Picture Shape Example A 2 and Linear H 2 / CO 2 AB 4 E Irregular SF 4 AB 2 tetrahedral (sea saw) AB 3 Triangular BCl 3 AB 3 E 2 T-shaped ClF 3 AB 2 E Angular or Bent PbI 2 AB 2 E 3 Linear XeF 2 AB 4 Tetrahedral CH 4 AB 6 Octahedral SF 6 AB 3 E Triangular pyramidal NH 3 AB 5 E Square pyramidal ClF 5 AB 2 E 2 Angular or Bent H 2 O AB 4 E 2 Square planar XeF 4 AB 5 Triangular bipyramidal PCl 5 AB 7 Pentagonal bipyramidal IF 7 Resonance What is resonance? NO 3 NO 2 XeO 3

5 Bonding/Lewis Dots Lecture Page 5 of 12 Date Isomers What is an isomer? Draw the three Lewis Structures for C 2 H 2 Cl 2 What are cis and trans structures? Free Radicals Draw the Lewis Structure for NO 2 Why does it dimerize? Lewis Acids and Bases

6 Bonding/Lewis Dots Lecture Page 6 of 12 Date Formal Charge How do you calculate formal charge? Draw three Lewis Structures for the sulfate ion. Calculate the formal charge on sulfur for each. Polarity How can we distinguish between a polar bond and a polar molecule Dipole moments H 2 HCl BCl 3 NH 3 How does symmetry effect a dipole moment?

7 Bonding/Lewis Dots Lecture Page 7 of 12 Date Why Hybridize? Remember the shapes of the orbitals: sp 3 Hybridization

8 Bonding/Lewis Dots Lecture Page 8 of 12 Date sp 2 Hybridization sp Hybridization

9 Bonding/Lewis Dots Lecture Page 9 of 12 Date dsp 3 Hybridization d 2 sp 3 Hybridization

10 Bonding/Lewis Dots Lecture Page 10 of 12 Date How do we determine the Hybrid Orbital Number? Number of things attached to the central atom Hybrid Orbital Number Geometry around the central atom Hybridization Delocalized Electron Model Benzene as predicted by Hybrid Orbital Model Benzene as predicted by Molecular Orbital Model

11 Bonding/Lewis Dots Lecture Page 11 of 12 Date Some Cool Molecules 1. For each of the following molecules or ions: a. Identify the central atom (or atoms) b. Draw the Lewis structure, and find from that the number of sigma bonds and the number of unshared pairs on the central atom. c. Identify the hybridization on the central atom. d. Determine the geometry of the atoms and lone pairs. e. Does the molecule have a dipole moment or other unusual features? CH 4 ClF 3 H 2 O PI 5 SF 6 I 3 BH 3 SF 4 NO 2 BeCl 2

12 Bonding/Lewis Dots Lecture Page 12 of 12 Date 1999 Answer the following questions using principles of chemical bonding and molecular structure. (a) Consider the carbon dioxide molecule, CO 2, and the carbonate ion, CO 3 2. (i) Draw the complete Lewis electron-dot structure for each species. (ii) Account for the fact that the carbon-oxygen bond length in CO 3 2 is greater than the carbon-oxygen bond length in CO 2. (b) Consider the molecules CF 4 and SF 4. (i) Draw the complete Lewis electron-dot structure for each molecule. (ii) In terms of molecular geometry, account for the fact that the CF 4 molecule is nonpolar, whereas the SF 4 molecule is polar CF 4 XeF 4 ClF 3 (a) Draw a Lewis electron dot structure for each of the molecules above and identify the shape of each. (b) Use the valence shell electron pair repulsion (VSEPR) model to explain the geometry of each of these molecules.

Polar bonds, polar molecules and the shape of molecules.

Chapter 3 Polar bonds, polar molecules and the shape of molecules. Polar and non-polar bonds In homonuclear diatomic molecules such as H 2 or Cl 2 electrons are shared equally between equal atoms. The