V.B. and M.O. methods, hyperconjugation

The electric dipole moment of a molecule is a valuable characteristic of its structure and also the value of the dipole moment is an important factor determining the cohesion energy. The relation between the dipole moment and the constitution, however, is complicated even for a diatomic molecule or one bond446. 

In the valence bond method the primary dipole has its origin in the contribution of ionic terms (p. 140). 

It is useful to divide the hydrocarbons with a conjugated system of bonds into the common, alternating hydrocarbons with exclusively rings with an even num- 

Here the charges as indicated are no longer the same for each carbon atom. Actually these hydrocarbons have a dipole moment (azulene 1.0 D, fulvene 1.2 D). 

The substances are also remarkable because they are coloured fulvene is the simplest coloured hydrocarbon. 

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B. DIPOLE MOMENT, NON-ALTERNATING HYDROCARBONS, COMPARISON OF V.B. AND M.O. METHODS, HYPERCONJUGATION... 

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