CHEM-C 117 Lecture Notes - Lecture 4: Valence Bond Theory, Lone Pair, Trigonal Bipyramidal Molecular Geometry
Document Summary
C117 chapter 10 notes- chemical bonding ii: molecular shapes, valence bond theory, and molecular orbital. Molecular structure determines properties: small structural changes cause large property changes, structure includes: Shape of molecule- described in terms of distances and angles in 3 dimensions. Electron geometry possible: draw lewis structure single/double/triple bond makes one region, other regions from unshared lone pairs on single nucleus. Molecular geometry/shape considers only spatial arrangements of atoms: lewis bonding theory predicts shapes of molecules. Basis for vsepr theory- valence shell electron pair repulsion. Axial positions- above and below central atom. Equatorial positions- same base plan as central atom. Equatorial atoms less crowded atom will be same. Lone pairs occupy equatorial plane first (up to 3 pairs: 6 groups- octahedral ((cid:891)(cid:882) ) If molecule contains bond pairs only, ideal bond angles correct. Bond/bond weakest: bond pair angles smaller than expected, ex. Trigonal pyramidal, (cid:883)(cid:882)(cid:889). (cid:887) between atoms; (cid:1840) angle reduced due to increased.
