Chapter 1-7: Introduction to Atomic Properties and Periodic Trends

Instructor's Style on Assessments:
- Worksheets and Quiz 2 questions are written by the instructor and reflect their question style.
- Active Chemistry homework questions are chosen from a question bank, not written by the instructor.
- Use worksheets for practice to get accustomed to the instructor's question format.
- Emphasis on understanding the why behind trends, not just memorizing the what.
Two Fundamental Questions for Understanding All Periodic Trends:
1. Where are the valence electrons? (i.e., in which principal quantum number (n) shell are they located?)
2. If the valence electrons are in the same n shell, how many protons are present in the nucleus?
Core Concepts:
- Valence Shell: The outermost electron shell containing valence electrons.
- Effective Nuclear Charge (Z_{eff}): The actual positive charge experienced by an electron from the nucleus. This is the net positive charge felt by an electron, considering the shielding effect of inner-shell electrons. Z_{eff} generally increases across a period due to increasing protons and constant shielding, and decreases down a group due to increased shielding and a larger principal quantum number.
- Shielding Effect: The reduction of the attractive force between an atomic nucleus and its outer electrons due to the presence of inner-shell electrons. Inner electrons effectively