This report presents x-ray scattering factors for neutral atoms from He to Lv and for most of the chemically significant ions through Lu³⁺, computed from numerical Hartree-Fock wave functions. The results are given in numerical tables and in the form of coefficients for an analytic function. The authors compare their results with those from other models, including the Thomas-Fermi-Dirac, Hartree, Hartree-Fock-Slater (HFS), and Dirac-Slater (DS) models. They conclude that the Hartree-Fock (HF) model provides the best approximation for free atoms, except for relativistic effects. The HF scattering factors for elements up to Kr (Z = 36) have been computed and tabulated. Mann has recently made extensive calculations of numerical HF wave functions, from which the authors have computed x-ray scattering factors for all neutral atoms through Lw (Z = 103) and most of the chemically significant ions through Lu (Z = 71). The scattering factors were computed from sinθ/λ = 0 to 1.50 at intervals of 0.01 Å⁻¹. The results are fitted to an analytic function, and the coefficients, along with the maximum and minimum percentage deviations of the analytic fit, are listed in Table II. The authors note that the results should be more accurate than previous calculations, although the differences between these scattering factors and those computed from analytic wave functions are not large. Relativistic effects are important for heavier elements, and the DS scattering factors are believed to be in error by being too large. The authors suggest that scattering factors calculated from a relativistic HF model should lie between the HF and DS scattering factors. However, until relativistic HF scattering factors are available, the HF or DS scattering factors should be equally useful for heavy elements. A deck of computer cards with the analytic coefficients may be obtained from the authors.This report presents x-ray scattering factors for neutral atoms from He to Lv and for most of the chemically significant ions through Lu³⁺, computed from numerical Hartree-Fock wave functions. The results are given in numerical tables and in the form of coefficients for an analytic function. The authors compare their results with those from other models, including the Thomas-Fermi-Dirac, Hartree, Hartree-Fock-Slater (HFS), and Dirac-Slater (DS) models. They conclude that the Hartree-Fock (HF) model provides the best approximation for free atoms, except for relativistic effects. The HF scattering factors for elements up to Kr (Z = 36) have been computed and tabulated. Mann has recently made extensive calculations of numerical HF wave functions, from which the authors have computed x-ray scattering factors for all neutral atoms through Lw (Z = 103) and most of the chemically significant ions through Lu (Z = 71). The scattering factors were computed from sinθ/λ = 0 to 1.50 at intervals of 0.01 Å⁻¹. The results are fitted to an analytic function, and the coefficients, along with the maximum and minimum percentage deviations of the analytic fit, are listed in Table II. The authors note that the results should be more accurate than previous calculations, although the differences between these scattering factors and those computed from analytic wave functions are not large. Relativistic effects are important for heavier elements, and the DS scattering factors are believed to be in error by being too large. The authors suggest that scattering factors calculated from a relativistic HF model should lie between the HF and DS scattering factors. However, until relativistic HF scattering factors are available, the HF or DS scattering factors should be equally useful for heavy elements. A deck of computer cards with the analytic coefficients may be obtained from the authors.