1. **Stating the problem:** Which element would you predict to have the highest first ionization energy among the given pairs: Neon or Carbon, Fluorine or Francium, Beryllium or Strontium, Iodine or Fluorine? 2. **Formula and concept:** First ionization energy is the energy required to remove the outermost electron from a neutral atom in the gaseous state. 3. **Important rules:** - Ionization energy generally increases across a period (left to right) in the periodic table because the nuclear charge increases, pulling electrons closer. - Ionization energy generally decreases down a group (top to bottom) because electrons are farther from the nucleus and more shielded. 4. **Analysis of each pair:** - Neon (Ne) vs Carbon (C): Both are in period 2, but Neon is a noble gas with a full outer shell, so it has a much higher ionization energy than Carbon. - Fluorine (F) vs Francium (Fr): Fluorine is in period 2, group 17, while Francium is in period 7, group 1. Fluorine has a much higher ionization energy because it is smaller and more electronegative. - Beryllium (Be) vs Strontium (Sr): Both are in group 2, but Beryllium is in period 2 and Strontium in period 5. Beryllium has higher ionization energy due to smaller atomic radius and less shielding. - Iodine (I) vs Fluorine (F): Both are halogens, but Fluorine is in period 2 and Iodine in period 5. Fluorine has higher ionization energy. 5. **Final answers:** - Highest ionization energy between Neon and Carbon: **Neon** - Highest ionization energy between Fluorine and Francium: **Fluorine** - Highest ionization energy between Beryllium and Strontium: **Beryllium** - Highest ionization energy between Iodine and Fluorine: **Fluorine** These predictions are based on periodic trends of ionization energy.