How do covalent bonds hold atoms together in organic compounds?

In organic compounds, atoms are held together by covalent bonds, which form when atoms share pairs of electrons. Because carbon is neither strongly electropositive nor electronegative, it is more likely to share its four outer-shell electrons than to gain or lose them, allowing it to form extensive, stable networks of bonds with itself and other elements like hydrogen, oxygen, and nitrogen.123

From a valence-bond perspective, these shared electron pairs reside between the nuclei of the bonded atoms, effectively linking them together. A more comprehensive view, molecular-orbital theory, explains that these electrons occupy a "bonding molecular orbital" that envelops the bonded atoms. This state is energetically favored because the electrons reach a lower energy level than they occupied in their separate atomic orbitals.3

Depending on the number of shared electron pairs, atoms may form single, double, or triple bonds, which dictate the molecule's specific three-dimensional architecture and chemical properties.12