theory of directed valence

The concept of directed valence in chemistry explains how atoms form bonds in specific spatial arrangements. This directional nature is a key characteristic of covalent bonds, distinguishing them from the nondirectional nature of ionic bonds.12

The Valence-Shell Electron-Pair Repulsion (VSEPR) theory, developed from earlier ideas by G.N. Lewis, posits that electron pairs (both bonding and lone pairs) around a central atom repel each other. The theory predicts that molecules will adopt shapes that minimize these repulsions, leading to specific geometric arrangements like tetrahedral or angular structures. For instance, the methane molecule (CH₄) is tetrahedral, and the water molecule (H₂O) is angular, with bond angles influenced by the repulsion between electron pairs. While VSEPR theory is a powerful predictive tool, it has limitations, such as not quantifying bond angles or lengths.12