We study the scattering of H-2 (v=0,J=0) molecules by the Pd(111) surface using classical trajectory methods. We show that the variation of the reflectivity with incidence angle can be explained with the combination of two processes: "dynamic trapping" and "direct dissociation" that verify total and normal energy scaling, respectively. The presence of the dissociation channel barely affects the angular distribution of scattered molecules. In the patterns of final angular distributions, the main difference, with respect to atom scattering, is a strong momentum transfer from motion normal to the surface toward molecular rotation. (C) 2003 American Institute of Physics.