Lecture Notes: Electron Configuration and Ions

Introduction

• Series assisting YouTuber Melissa Lucy Kenton in Chemistry.
• Reminder to download a free study plan with videos and resources.

Electron Configuration Recap

• Example: Iron (Fe)
  • Configuration: 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d⁶.

Understanding Ions

• Ions: Elements with a charge.
• Positive Charge: Electrons are subtracted.
• Negative Charge: Electrons are added.
• Example: Fe²⁺
  • Remove two electrons from the 4s subshell, not the 3d subshell.
  • Energy consideration: 4s has lower energy than 3d.

Stability and Electron Removal

• D Sublevel: Prefers to be half full (5) or completely full (10).
• Rule: Remove electrons from the highest energy subshell first (e.g., 4s before 3d).

Electrons and Energy Levels

• Energy levels do not strictly follow ordinal numbers.
• Comparison: 4s vs. 3d and energy considerations.

Sulfur Example

• Configuration for Sulfur in its neutral state.
• Negative Charge: Add electrons to fill up to p⁶ (maximum for P subshell).

Exceptions to Electron Configuration

• Common Exceptions: Chromium (Cr) and Copper (Cu).
• Reason: Stability in electron configurations due to experimental findings.
• Prioritize memorizing these exceptions.

Valence and Core Electrons

• Valence Electrons: Outermost electrons, significant for chemical bonding.
• Finding Valence Electrons:
  • Determine by the highest energy level (n value).
  • Example: Highest n = 4, add electrons in 4s and 4p.
• Core Electrons: All other electrons apart from valence ones.

Next Steps

• Prepare for practice problems in the next video.

These notes summarize key points from the lecture, focusing on electron configurations, ion formation, energy levels, and exceptions to typical rules. Understanding these will aid in solving related chemistry problems.