Within the tight-binding approximation, the binding energy of a condensed system can be expanded to individual atoms. These site-specific binding energy terms (SBEs) are calculated for a Si(111)-(7x7) surface. We find that the SBEs of the adatoms agree well with the desorption energies of the corresponding adatoms, in terms of both the relative values measured in experiments [Uchida et al., Phys. Rev. Lett. 70 (1993) 2040] and the absolute values estimated from the available results of ab initio calculations. On the basis of this result, a bond-responsive relaxation property of the substrate responding to the desorption of single adatoms can be deduced. That is, if an adatom is extracted, the relaxation energy of the substrate will be half of the bond-counting energy between the adatom and the substrate in the original (before extraction) configuration. This relaxation property is generalized to be a so-called bond-responsive relaxation model; its condition of applicability is discussed and a test case is presented.