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Why do lone pairs not directly hold two atoms together?

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Diagram showing the formation of a polar covalent bond in a water molecule, with two hydrogen atoms bonding to one oxygen atom to form H2O, illustrating shared electrons and chemical reaction. — covalent bond In polar covalent bonds, such as that between hydrogen and oxygen atoms, the electrons are not transferred from one atom to the other as they are in an ionic bond. Instead, some outer electrons merely spend more time in the vicinity of the other atom. The effect of this orbital distortion is to induce regional net charges that hold the atoms together, such as in water molecules.

In the context of Lewis structures, a covalent bond is defined by a shared electron pair that resides between two atomic nuclei, effectively lowering the total energy of the system by allowing the electrons to experience the attraction of both centers simultaneously.12

Lone pairs, by contrast, are pairs of electrons that remain associated with a single atom and do not participate directly in the bonding between two atoms. Because they are not positioned between two nuclei, they do not contribute to the electrostatic attraction that holds those specific atoms together.13

While lone pairs do not form bonds, they are still significant in determining molecular shape. According to VSEPR theory, all electron pairs—both bonding pairs and lone pairs—exert repulsive forces on one another. Consequently, lone pairs influence the geometry of a molecule by occupying space and pushing against other electron pairs to minimize repulsion, even though they do not serve as the "glue" connecting the atoms.3