Exothermic chemical and ionic reactions are grouped into sources and losses for individual ions and minor neutral species. Thus, each reaction is listed at least twice: for every source there are one or more sinks, and there may be more than one source for some species. (There are a few exceptions involving minor species.) The major neutral species, N2, O2 and O, are end products, following the scheme of Figure 5.4.1. The chemical equations are listed with the excess kinetic energy of the reaction and the rate coefficient that is currently most widely accepted. Reaction rate coefficients are obtained, primarily, from laboratory measurements but a few are derived from atmospheric data and modelling and from theoretical work. Some are still controversial. The numerical values listed in Table A5.1 are derived from numerous references in the research literature and are applicable in the temperature range encountered in the thermosphere.