For the low energy x‐ray region of 100‐2000 eV, the complete atomic interaction, coherent scattering and photoelectric absorption can be desribed by a complex scattering amplitude which may be given through the atomic scattering factor, f1+if2. For this low photon energy region, it is shown by the relativistic quantum dispersion theory that the atomic scattering factors can be uniquely determined from simple relations involving only the atomic photoionization cross section dependence upon photon energy. We have compiled ‘‘state of the art’’ tables for the photoionization cross sections for 94 elements and for the photon energy region of 30−100,000 eV. With this compilation, we have established atomic scattering factor tables for the 100−2000 eV region. By a summing of the complex, atomic scattering amplitudes, a low energy x‐ray interaction can be determined. Even for atoms in the molecular or solid state the scattering cross sections remain atomic‐like except for photon energies very near the thresholds. Using practival examples, the methods of calculation, with the atomic scattering factors, are reviewed here for the followig: 1) x‐ray energy deposition within materials (energy response of x‐ray photocathodes); 2) transmission through a homogeneous medium: refraction; 3) transmission through a random collection of uniform spheres: low angle scattering in an inhomogeneous medium; 4) specular, Fresnel reflection (total and large angle reflection) at smooth boundry; and 5) Bragg reflection from a periodic, layered system‐(reflection by crystals and multilayers).