An example of the former is empirical packing energy calculations, where only interactions between adjacent atoms are considered.
Delocalized electrons are contained within an orbital that extends over several adjacent atoms.
In a 1,2 shift, the substituent moves between two adjacent atoms.
A peak in scattering intensity is observed when the cones line up such that each passes over the adjacent atom.
The related term vicinal refers to the relationship between two functional groups that are attached to adjacent atoms.
Electrons remain bound to atoms but are able to transfer to adjacent atoms.
For carbon, the sigma overlap between adjacent atoms is sufficiently strong that perfectly stable chains can be formed.
It is impossible to assign (+) and (-) polarities to a 3-membered ring without having two adjacent atoms with the same polarity.
In a 1,2 shift the movement involves two adjacent atoms but moves over larger distances are possible.
As ylides, they possess a negative charge and a positive charge on adjacent atoms.