[填空题]
In the ionic salt KF, the separattpte * esnz.y;u aqed*0331eqion distan0p5-8tk+mc5a .zys*rolkdh ;adpy c9 ce between ions is about 0.27 nm.
(a) Estimate the electrostatic potential energy between the ions assuming them to be point charges (magnitude $ 1e $). PE = eV
(b) It is known that F releases 4.07 eV of energy when it "grabs" an electron, and 4.34 eV is required to ionize K. Find the binding energy of KF relative to free K and F atoms, neglecting the energy of repulsion. Binding energy = eV