[en] The reactions of O(³P) with six prototypical unsaturated hydrocarbons, and the reaction of O(¹D) with HD, have been studied in high-resolution crossed-molecular-beams scattering experiments with mass-spectrometric detection. The observed laboratory-product angular and velocity distributions unambiguously identify parent-daughter ion pairs, distinguish different neutral sources of the same ion, and have been used to identify the primary products of the reactions. The derived center-of-mass product angular and translational energy distributions have been used to elucidate the detailed reaction dynamics. These results demonstrate that O(³P)-unsaturated hydrocarbon chemistry is dominated by single bond cleavages, leading to radical products exclusively