Which of the following statements about ionization energy is true?. A. In a period, elements farther to the right generally have lower ionization energies than elements on the left. . B. Elements toward the bottom of a group periodic table generally have higher ionization energies than elements at the top of the group. . C. Ionization energy is the amount of energy used to add an electron to an atom. . D. Potassium has a lower ionization energy than sodium.