Example Exercises The following series of problems reviews general understanding of the aforementioned material. Exercises 1. Based on the periodic trends for ionization energy, which element has the highest ionization energy? 2. Which has a larger atomic radius: nitrogen or oxygen? 3. Which element is more electronegative, sulfur (S) or selenium (Se)? 4. Why is the electronegativity value of most noble gases zero? 5. Rewrite the following list in order of decreasing electron affinity: fluorine (F), phosphorous (P), sulfur (S), boron (B). 6. Which of these elements has a smaller atomic radius than sulfur (S): O, Cl, Ca, Li Answer 1 Helium (He). Answer 2 Atomic radius increases from right to left on the periodic table. Therefore, nitrogen is larger than oxygen. Answer 3 Sulfur (S). Note that sulfur and selenium share the same column. Electronegativity increases up a column. This indicates that sulfur is more electronegative than selenium. Answer 4 Because of their full valence electron shell, the noble gases are extremely stable and do not readily lose or gain electrons. Answer 5 Fluorine (F)>Sulfur (S)>Phosphorous (P)>Boron (B). Explanation: Electron affinity generally increases from left to right and from bottom to top. Answer 6 Oxygen (O) is the only element in the list with a smaller atomic radius than S. Periodic trends indicate that atomic radius increases down a group (from top to bottom) and from left to right across a period.