The resonant scattering length for K-shell absorption and an E2 transition is calculated for 3d transition ions, on the basis of an atomic model. It is applied to the evaluation of the intensity of x-rays Bragg reflected from a magnetic salt, e.g. NiO, and the circular dichroic signal in the attenuation coefficient. The information which can be extracted from these quantities relates to the orbital properties of the 3d valence shell. An exception is the s-state ion , for which the leading-order effect is zero. For the ion it is shown that inclusion of core polarization in the calculation leads to a weak effect which contains the spin magnetic moment.