Resonance, among bond structures class

At the present time there is no satisfactory theory of these particles. It seems likely, however, that some of them may be classed with the fundamental particles (see the following section), and that others may be described as complexes of two or more fundamental particles, possibly with resonance among several structures, roughly analogous to the resonance of molecules among several valence-bond structures. 

In recent years it has become clear that the structure of metals and alloys may be described in terms of covalent bonds that resonate among the alternative interatomic positions in the metals, and that this resonance is of greater importance for metals than for substances of any Other class, including the aromatic hydrocarbons. Moreover, the phenomenon of metallic resonance of the valency bonds must be given explicit consideration in the discussion of metallic valency it is necessary in deducing the metallic valency from the number of available electrons and bond orbitals to assign to one orbital a special r le in the metallic resonance. 

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