CHM120H5 Lecture Notes - Lecture 26: Steric Number, Vsepr Theory, Lone Pair
Document Summary
1. count all vse-s of the central atom, a. 2. add e-s from the ligands, x: if ligand has add. 5. distribute e- pairs so as to minimize e-pair repulsions. 6. distort from regular geometry if e- pairs are not equivalent. Electron count for arriving at steric number (sn) Here a is the central atom and x is the atom bonded to it. For example if ccl4 is the molecule then a = c and x = cl and n= 4. Now for the electron count, take the valence electrons of a add to that the electron contribution from x. How to find the electron contribution from x. If the molecular ion has negative charges add that to the total electron count and if it has positive charges subtract that from th electron count. When sn = 4 the basic shape is tetrahedral, but we have only three atoms in nh3.
