This third part of the series is a study on the relation between the rate coefficients of atomic transitions and other atomic properties. The insight into scaling laws is needed to support the study of the impact of equilibrium departures on the atomic state distribution function in plasmas, especially inductively coupled plasmas. Only global trends are considered for which a classical approach suffices. Comparison with results of more elaborate theories shows that the results of this classical approach are sufficiently good. Apart from the study of classical hydrogenic scaling laws, some attention is paid to the properties of non-hydrogenic atoms and ions.