The third ionization energy of bromine is the energy required for which of the following processes?

• A. Br^{2+} (g) → Br^{3+} (g) + e^{-}
• B. Br^{-} (g) → Br (g) + e^{-}
• C. Br^{+} (g) → Br^{2+} (g) + e^{-}
• D. Br (g) → Br^{+} (g) + e^{-}

Answer: (A)

Verified step by step guidance

1. Understand that the third ionization energy refers to the energy required to remove the third electron from an atom or ion in the gas phase.
2. Recall the sequence of ionization energies: the first ionization energy removes the first electron from the neutral atom, the second ionization energy removes the second electron from the resulting +1 ion, and the third ionization energy removes the third electron from the +2 ion.
3. Identify the species involved in the third ionization energy process: it starts with the ion that has already lost two electrons, which is Br^{2+} (g).
4. Write the ionization process for the third ionization energy as the removal of one electron from Br^{2+} (g), resulting in Br^{3+} (g) plus an electron: \(\mathrm{Br^{2+} (g) \rightarrow Br^{3+} (g) + e^{-}}\).
5. Compare this with the given options to confirm that the correct process corresponds to the third ionization energy.