A pair of valence electrons not involved in bonding with other atoms is referred to by a specific term in chemistry. These electron pairs, also known as non-bonding pairs, reside on an individual atom. For example, in a water molecule (HO), the oxygen atom possesses two such pairs of electrons, which are not shared with the hydrogen atoms through covalent bonds. Instead, they remain localized on the oxygen atom.
The presence of these non-bonding electron pairs significantly influences molecular geometry and reactivity. They exert a greater repulsive force than bonding pairs, impacting the arrangement of atoms in a molecule as described by VSEPR theory. Historically, the understanding of their role has been crucial in predicting and explaining molecular shapes, dipole moments, and reaction mechanisms, leading to advancements in fields such as drug design and materials science.
