Chemical Bonds Versus Approach Preferences in Crystals

6 Chemical Bonds Versus Approach Preferences in Crystals 

The last sections have shown that the strength of chemical interactions can nowadays be evaluated rather easily and reliably, but is it possible, convenient, necessary, or indispensable to define a chemical bond in a general conceptual way. 

The following is a tentative description of a chemical bond in terms of a few basic principles  

A chemical bond is a localized phenomenon that brings about a stable linkage between two atomic nuclei. A chemical bond must result from the interaction between the electron distributions in the basins close to the two involved atomic nuclei. The identification of the bond must not be sensitive to changes of the chemical environment (e.g., by induction effects). 

A chemical bond produces proximity of the two involved atomic nuclei, whose separation must be less than the sum of commonly accepted random-contact radii (if there is arguing about the exact value of the contact radii then the coimection is not a chemical bond). This is a necessary but not sufficient condition. Especially in the intermolecular case, proximity between two nuclei does not always imply a chemical bond. 

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