AP Chemistry Questions on Periodic Trends: A Comprehensive Test

🧪 Quick Study Guide

• ⚛️ Atomic Radius: Generally increases down a group (more energy levels) and decreases across a period (increased nuclear charge).
• ⚡ Ionization Energy: Energy required to remove an electron. Generally decreases down a group (valence electrons further from nucleus) and increases across a period (increased nuclear charge).
• 🧲 Electronegativity: Ability of an atom to attract electrons in a chemical bond. Generally decreases down a group and increases across a period (excluding noble gases).
• 🔩 Metallic Character: How readily an atom can lose electrons. Generally increases down a group and decreases across a period.
• 🛡️ Effective Nuclear Charge ($Z_{eff}$): The net positive charge experienced by an electron in an atom. $Z_{eff} = Z - S$, where $Z$ is the atomic number and $S$ is the number of shielding electrons.
• 📈 Trends and Stability: Elements strive to achieve a stable electron configuration (like noble gases). Trends reflect the forces governing electron behavior.

Practice Quiz

1. Which of the following elements has the largest atomic radius?
   1. Cl
   2. Na
   3. Mg
   4. S
2. Which of the following elements has the highest ionization energy?
   1. K
   2. Na
   3. Li
   4. Cs
3. Which of the following elements has the highest electronegativity?
   1. Na
   2. Mg
   3. Al
   4. Si
4. Which of the following elements has the greatest metallic character?
   1. P
   2. S
   3. Cl
   4. Na
5. Which of the following correctly ranks the elements in order of increasing atomic radius?
   1. S < Cl < K
   2. Cl < S < K
   3. K < S < Cl
   4. Cl < K < S
6. Which of the following correctly ranks the elements in order of increasing ionization energy?
   1. Na < Mg < Al
   2. Al < Mg < Na
   3. Mg < Na < Al
   4. Na < Al < Mg
7. Which of the following elements has the largest effective nuclear charge ($Z_{eff}$) experienced by its valence electrons?
   1. Na
   2. Mg
   3. Al
   4. Si