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Why can hydrogen form a stable covalent bond with chlorine?

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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.

Hydrogen and chlorine form a stable covalent bond because sharing an electron pair allows both atoms to achieve a lower total energy state compared to when they are widely separated.12

By sharing a pair of electrons, each atom attains a closed-shell electronic structure, often described by the octet rule. In this arrangement, the shared electrons occupy the space between the two nuclei, where they are attracted to both centers simultaneously. This positioning results in a lower energy state than if the electrons were only under the influence of a single nucleus.12

While the bond is covalent, it is also polar because chlorine is more electronegative than hydrogen. Consequently, the shared electron pair is drawn more strongly toward the chlorine atom, creating partial charges on the atoms. This stability is a result of the system reaching a configuration that minimizes its overall energy.321