CEM 141 Lecture Notes - Lecture 29: Triple Bond, Sigma Bond, Valence Electron
Document Summary
In c2h2, there is a triple bond between the two carbons. Formal charge = (valence electron on free atom) - (# bonds to atom) - (# non-bonded electrons) Fc (o) = 6 - 3 - 2 = +1. Fc (n) = 5 - 4 - 0 = +1. Fc (o) = 6 - 1 - 6 = -1. Fc (h) = 1 - 1 - 0 =0. Helps figure out shape of molecules from the lewis structure. How? assume all centers of electron density* repel each other. There is a minimum energy arrangement that the atom will naturally take up. *a lone pair is a center of density and bonds are centers of density. lone pairs and single, double, and triple bonds each count as 1 center. Note: lone pairs and single, double, and triple bonds each count as 1 center. Multiple bonds count as one center of electron density in vsepr. A single bond is always a sigma bond.
