The detailed dynamics of collision induced desorption are studied for the scattering of an Ar atom from an N2 molecule adsorbed on the W(100) surface. The interaction potentials needed for the simulations were constructed using all the available experimental and theoretical data. We find a strong dependence of the various quantities and distribution functions of scattered atoms and desorbed molecules on the angle of incidence of the atomic beam. This dependence on the angle of incidence is related to the existence of two pathways for reactive events. The first reaction mechanism is related to a collision between the atom and the adsorbate followed by the collision of the atom with the surface, this is termed as a direct reactive, DR, event. The second pathway to reaction corresponds to a collision between the atom and the surface followed by a collision with the adsorbate. This mechanism will be termed as an indirect reactive, IDR, event. It was found that for near normal angle of incidence only the DR pathway is operative, while for off-normal angles of incidence both DR and IDR mechanisms operate.