What does one line between atoms represent in a structural formula?

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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 a structural formula, a single line between two atoms represents a single bond, which is a type of covalent bond where the two atoms share one pair of electrons.12

This shared electron pair is often referred to as a bonding pair. While structural formulas use these lines to indicate the connectivity and arrangement of atoms within a molecule, they do not always represent the actual three-dimensional shape of the compound.23