Triple Bonds, More Recent Picture

DOUBLE AND TRIPLE BONDS, MORE RECENT PICTURE 

Two drawings of ethylene appear below. The first attempts to show overlap between neighboring dumbbell electrons. The second picture is stretched out so that the portions of the molecule may be more clearly labeled (although the interaction between the r electrons then becomes 

The ring compound, benzene, C6H6, is given in a tr-bond picture only but a similar streamer picture can be drawn for it also, showing clouds of electric charge above and below the plane of the ring. 

The classical formulae of the two hydrocarbons are given in the same figure below the more modern formulae. It is seen that the classical formulae of butadiene put a single bond between the two center carbon atoms the streamer picture, however, shows that the middle bond has some double bond character also. It is seen that the x-bond picture of benzene can correspond to either of the two Kekule forms but is better than either alone because it does not convey the erroneous impression that three of the six C—C bonds are single bonds. 

Electron delocalization is most extreme in solid and liquid metals. Here valence electrons are spread over not two, four, or six atoms, but over the entire crystal network. The extreme mobility of electrons accounts for their typically high electrical and thermal conductivity. Non-loealized electrons carry an electric current more effectively than any other species, and, because of their slight weight, are particularly quick to respond to thermal disturbance. 

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