The one-electron term of the Breit–Pauli Hamiltonian multiplies this quantity to a spin–orbit interaction term over a double summation. Using the “self-consistent field” method, this quantity equals the ratio of the expectation for the radius of a hydrogen orbital to that of a hydrogen-like orbital. This quantity multiplies radius in the exponential term of a Slater-type orbital. Factors of 0.30 and 0.35 for various orbitals are used to calculate this quantity by Slater’s rules. This quantity is divided by the square of covalent radius to obtain the Allred–Rochow electronegativity. Shielding from inner-shell (10[1])electrons decreases this quantity below the atomic number. (10[1])For 10 points, name this quantity that roughly describes the electric force experienced by an electron in an atom, denoted “Z-sub-e-f-f.” (-5[1])■END■ (0[1])