Key Concepts: VSEPR & Molecule Shapes

Core Definitions

• VSEPR Theory: Valence Shell Electron Pair Repulsion — electron pairs around a central atom arrange to minimize repulsion.
• Linear: 2 bonding pairs, 0 lone pairs → 180° bond angle (e.g., CO₂).
• Trigonal Planar: 3 bonding pairs, 0 lone pairs → 120° bond angle (e.g., BF₃).
• Tetrahedral: 4 bonding pairs, 0 lone pairs → 109.5° bond angle (e.g., CH₄).
• Bent: 2 bonding pairs, 1-2 lone pairs → less than 120° or 109.5° (e.g., H₂O).
• Lone Pairs: Non-bonding electron pairs that take up space and compress bond angles.