The (100) and (111) surfaces of gold reconstruct in such a way as to increase the density of surface atoms, this being thought to result from large tensile stresses in the ideal surfaces. The authors present self-consistent electronic structure calculations of unreconstructed Au(100) using the surface embedded Green function approach. The surface charge density shows increased bond-charge in the first and second layers which, by a Hellmann-Feynman theorem, leads to attractive surface stresses. This enhancement of surface bonds is shown to be a quite general property of s-band metals and is a consequence of surface band narrowing. The same features are included implicitly in the 'glue model' which has proved successful in describing gold reconstructions.