re-extraction [obsolete] , 1255 reactance, , 1255 reactant, 1255 reacting bond rules, 1256 reaction, 1256 reaction barrier, 1256 reaction chromatography, 1256 reaction coordinate, 1257 reaction cross-section, , 1257 reaction dynamics, 1258 reaction injection moulding, 1258 reaction intermediate, 1258 reaction path, 1258 reaction path degeneracy, 1259 reaction probability, , 1259 reaction stage, 1259 reaction step, 1259 reaction time, 1260 reactive adsorption, 1260 reactive blending, 1260 reactive complex, 1260 reactive polymer, 1261 reactive polymer processing, 1261 reactive (reactivity), 1261 reactive scattering, 1261 reactivity index, 1262 reactivity–selectivity principle (RSP), 1262 readability of a balance , 1263 reading, 1263 reagent, 1263 real (electrified) interphase, 1263 real potential of a species in a phase, 1263 real surface (interface) area, 1264 rearrangement, 1264 rearrangement ion in mass spectrometry , 1264 rearrangement stage, 1264 rebound reaction, 1265 receptor, 1265 receptor in drug design , 1265 recognition site, 1265 recoil in radioanalytical chemistry , 1266 recoil labelling, 1266 recoil-free fraction in Mössbauer spectrometry , 1266