1. Lewis Structures, VSPER, Electron Domain and Molecular Geometry, Hybridization

2. How to draw them Add up all the valence electrons for all the atoms involved in bonding. Connect the atoms to the central atom with single bonds Calculate the number of electrons remaining by subtracting 2 electrons for every bond form. Use the remaining electrons to achieve noble gas configurations

3. Expanded Octet - central atom ends up with more than an octet Applying the “expanded octet”: The central atom with an expanded octet MUST have an atomic number larger than 10 (beyond neon). The central atom with an expanded octet CANNOT have double or triple bonds. For our purpose any ‘extra’ electrons left after each atom has noble gas config. will go on the central atom BrF 3 SF 4 XeF 5 + ICl 3 XeOF 4

4. VSEPR Theory Valence shell electron pair repulsion theory Molecule shape based on electrons repelling one another Electrons are always in pairs

5. E- density vs. Molecular shape Shape of the e- clouds in space Include sigma bonds and unshared pairs Coordination # Chart on h/o Considers only the shape/ angles between nuclei Unshared pairs affect shape Chart in book

6.  Must Know  Coord. #Cloud ShapeBond angle Hybridization 2Linear180 o sp 3Trigonal planar120 o sp 2 4Tetrahedral109.5 o sp 3 5Trigonal bipyramidal 90 o and 120 o sp 3 d 6Octahedral90 o sp 3 d 2

7. Molecular Shapes AB 2 Linear AB 3 Trigonal planar AB 4 Tetrahedral AB 5 Trigonal bipyramidal AB 6 Octahedral AB 3 E Angular or Bent AB 3 E Trigonal pyramidal AB 3 E 2 Angular or Bent AB 4 E Irregular tetrahedral (see saw) AB 3 E 2 T-shaped AB 2 E 3 Linear AB 6 E Square pyramidal AB 5 E 2 Square planar

8. Polar Molecules Molecules with a positive and a negative end Requires two things to be true ¬ The molecule must contain electronegative element that causes the polar bond -This can be determined from differences in electronegativity. ­ Symmetry can cancel out the net effect of the polar bonds. -Must determine geometry first.

9. Determining Molecular Polarity Nonpolar Molecules Dipole moments are symmetrical and cancel out. BF 3 F F F B Courtesy Christy Johannesson www.nisd.net/communicationsarts/pages/chem

10. s pxpx pypy pzpz Carbon 1s 2 2s 2 2p 2 Carbon could only make two bonds if no hybridization occurs. However, carbon can make four equivalent bonds. sp 3 hybrid orbitals Energy sp 3 C atom of CH 4 orbital diagram B A B B B Brown, LeMay, Bursten, Chemistry The Central Science, 2000, page 321

11. Hybridization Involving d Orbitals 3s 3p 3d promote five sp 3 d orbitals 3d3d F F F P F F A BeBe BeBe BeBe BaBa BaBa Trigonal bipyramidal hybridize degenerate orbitals (all EQUAL) unhybridized P atom P = [Ne]3s 2 3p 3 vacant d orbitals