The Valence Shell Electron Pair Repulsion (VSEPR) theory is a model used in chemistry to predict the 3D shape of molecules based on the idea that electron pairs around a central atom repel each other and will arrange themselves as far apart as possible to minimize repulsion.

VSEPR considers:

• Bonding pairs (shared electrons between atoms)
• Lone pairs (non-bonding electrons on the central atom)

These electron pairs determine the geometry of the molecule. Some common shapes include:

• Linear (e.g., CO₂)
• Trigonal planar (e.g., BF₃)
• Tetrahedral (e.g., CH₄)
• Trigonal pyramidal (e.g., NH₃)
• Bent (e.g., H₂O)

Lone pairs take up more space than bonding pairs, often causing bond angles to shrink and shapes to become distorted.

VSEPR theory is essential for understanding molecular geometry, which influences physical properties, reactivity, polarity, and biological function of molecules.