What basic principle of physics governs VSEPR theory?
electrostatic repulsion between similar charges
VSEPR Theory tells us about the arrangement of lone pairs and bonding pairs around a central atom, giving a molecule its shape and bond angles. Electron pairs (both lone pairs and bonding pairs) repel each other to get as far apart as possible. Lone pairs, being held more tightly to their corresponding atom, repel more strongly than bonding pairs.