BU Dental Radiology Practice Exam 2026 – Complete Study Resource

Binding energy is the energy needed to remove an electron from an atom. The electrostatic pull from the nucleus is stronger on electrons that are closer, because the distance is shorter and shielding by other electrons is less effective for inner shells. With this stronger attraction, more energy is required to liberate the electron, so its binding energy is higher. Electrons farther from the nucleus feel a weaker net pull due to greater distance and more shielding, yielding lower binding energies. Therefore, electrons nearer the nucleus have higher binding energy, making the statement that binding energy increases for electrons closer to the nucleus the best description.