periodic table trends examples

📚 Quick Study Guide

• ⚛️ Atomic Radius: The size of an atom. Generally, it increases down a group (due to added electron shells) and decreases across a period (due to increased nuclear charge).
• ⚡ Ionization Energy: The energy required to remove an electron from an atom. It generally decreases down a group (electrons are further from the nucleus) and increases across a period (stronger nuclear attraction).
• ➕ Electronegativity: The ability of an atom to attract electrons in a chemical bond. It generally decreases down a group (larger atomic size) and increases across a period (greater nuclear charge). Fluorine is the most electronegative element.
• Metallic Character: How readily an element loses electrons. Metallic character increases down and to the left on the periodic table.
• $Effective Nuclear Charge (Z_{eff})$: $Z_{eff} = Z - S$, where $Z$ is the atomic number and $S$ is the number of shielding electrons. This influences many periodic trends.

🧪 Practice Quiz

1. Which of the following elements has the largest atomic radius?
   1. A. Fluorine (F)
   2. B. Chlorine (Cl)
   3. C. Bromine (Br)
   4. D. Iodine (I)
2. Which of the following elements has the highest ionization energy?
   1. A. Sodium (Na)
   2. B. Potassium (K)
   3. C. Rubidium (Rb)
   4. D. Cesium (Cs)
3. Which of the following elements is the most electronegative?
   1. A. Oxygen (O)
   2. B. Sulfur (S)
   3. C. Selenium (Se)
   4. D. Tellurium (Te)
4. Which of the following elements has the greatest metallic character?
   1. A. Carbon (C)
   2. B. Silicon (Si)
   3. C. Germanium (Ge)
   4. D. Tin (Sn)
5. Going across a period from left to right, what generally happens to the effective nuclear charge ($Z_{eff}$)?
   1. A. It decreases
   2. B. It increases
   3. C. It remains the same
   4. D. It fluctuates randomly
6. Which element would you expect to have the *lowest* ionization energy?
   1. A. Nitrogen (N)
   2. B. Phosphorus (P)
   3. C. Arsenic (As)
   4. D. Bismuth (Bi)
7. Which of these is the best explanation for why atomic radius decreases across a period (from left to right)?
   1. A. The number of electron shells increases.
   2. B. The number of neutrons increases.
   3. C. The effective nuclear charge increases, pulling electrons closer.
   4. D. The effective nuclear charge decreases, allowing electrons to move further away.