AP Chemistry

Advanced Placement Chemistry exploring atomic structure, chemical bonding, and reactions.

Structure of the AtomElectron Configuration and Periodic TrendsTypes of Chemical Bonds
Molecular Geometry and VSEPR TheoryTypes of Chemical ReactionsStoichiometry and Chemical Calculations
Chemistry in MedicineEnvironmental ChemistryMaterials Science and Everyday Products
Mastering Multiple ChoiceSolving Free-Response Problems
Structure of the Ato...Electron Configurati...Types of Chemical Bo...Molecular Geometry a...Types of Chemical Re...Stoichiometry and Ch...Chemistry in Medicin...Environmental Chemis...Materials Science an...Mastering Multiple C...Solving Free-Respons...
Advanced Topics

Molecular Geometry and VSEPR Theory

Predicting Molecular Shapes

The Valence Shell Electron Pair Repulsion (VSEPR) theory helps predict the 3D shapes of molecules based on repulsion between electron pairs.

  • Electron pairs (bonding and lone pairs) arrange themselves as far apart as possible.
  • Common shapes include linear, bent, trigonal planar, tetrahedral, trigonal bipyramidal, and octahedral.

Bond Angles

Each geometry has characteristic bond angles, which influence molecular properties like polarity and reactivity.

Real-World Example

The bent shape of water molecules gives it unique properties, like high surface tension.

Key Formula

\[\text{AX}_n\text{E}_m\]

Examples

  • Methane (CH₄) is tetrahedral.

  • Ammonia (NH₃) is trigonal pyramidal.

In a Nutshell

VSEPR theory predicts molecular shapes by considering electron pair repulsion.

Key Terms

VSEPR
A model used to predict the shape of molecules based on electron pair repulsion.
Bond Angle
The angle formed between three atoms across at least two bonds.
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Types of Chemical Reactions