Motivated by quantum chemistry calculations, showing that molecular adsorption in graphene takes place on preferential sites of the honeycomb lattice, we study the effect of an isolated impurity on the local electronic properties of a graphene monolayer, when the impurity is located on a sitelike, bondlike, or hollowlike position. We evaluate the local density of states (LDOS) as a function of energy on the impurity and on its neighboring sites, as well as in reciprocal space, at an energy corresponding to a bound state, in the three cases of interest. The latter study may be relevant to interpret the results of Fourier-transformed scanning tunneling spectroscopy, as they show which states mostly contribute to impurity-induced variations in the LDOS. We also estimate, semianalytically, the dependence of the condition for having a low-energy bound state on the impurity potential strength and width. Such results are then …