🧪 Topic Summary
Periodic table trends are specific patterns that are present in the periodic table that illustrate different aspects of a certain element, including its size and its electronic properties. The major periodic trends include electronegativity, ionization energy, electron affinity, atomic radius, metallic character, and ionic radius. Understanding these trends allows us to predict how elements will react and behave.
These trends arise from the interplay between the effective nuclear charge ($Z_{eff}$) experienced by valence electrons and the electron configuration of the elements. As you move across a period (row) from left to right, the effective nuclear charge generally increases, leading to stronger attraction between the nucleus and valence electrons. As you move down a group (column), the principal quantum number (n) increases, and the valence electrons are farther from the nucleus, resulting in weaker attraction. These two factors give rise to the periodic trends.
⚛️ Part A: Vocabulary
Match each term with its definition:
| Term |
Definition |
| 1. Electronegativity |
A. The energy required to remove an electron from a neutral atom in the gaseous phase. |
| 2. Ionization Energy |
B. The distance from the nucleus to the outermost electron. |
| 3. Atomic Radius |
C. The ability of an atom to attract electrons in a chemical bond. |
| 4. Electron Affinity |
D. The energy change when an electron is added to a neutral atom to form a negative ion. |
| 5. Metallic Character |
E. How readily an atom loses electrons and forms positive ions. |
📝 Part B: Fill in the Blanks
As you move across a period from left to right, the ______________ generally increases, while the ______________ decreases. Moving down a group, the atomic radius ______________ and the ionization energy ______________. Elements with high electronegativity tend to ______________ electrons.
🤔 Part C: Critical Thinking
Explain how the effective nuclear charge ($Z_{eff}$) influences the trends in ionization energy and atomic radius across a period. Use examples from the periodic table to support your explanation.