Answer:
Fluorine
Step-by-step explanation:
Ionization energy is the energy required to remove an electron from an atom or a negative ion. Fluorine (F) is a highly electronegative element, meaning it has a strong tendency to attract electrons. When fluorine gains an electron to become the fluorine negative ion (− F ), it forms a stable, closed-shell configuration, and removing an electron from this stable configuration requires more energy. In summary, the ionization energy of fluorine is higher than that of fluorine negative ( − F ).