What defines a covalent bond in chemistry?

A covalent bond is specifically defined by the sharing of electron pairs between atoms. This type of bond occurs when two atoms come close enough for their outermost electron shells to overlap, allowing them to share one or more pairs of electrons. This sharing leads to a stable arrangement of electrons, which is vital for the formation of molecules. The strength and stability of covalent bonds can vary depending on the number of shared electron pairs (single, double, or triple bonds), but their defining characteristic remains the cooperative sharing of electrons, which differentiates them from other types of bonds such as ionic or transient bonds.

In contrast, other options do not accurately capture this primary characteristic of a covalent bond. Transient bonds do not involve persistent electron sharing, while electrostatic attraction describes ionic bonds rather than covalent bonds. Additionally, while covalent bonds can be weaker than some ionic bonds under certain conditions, this quality is not a defining feature of covalent bonds in general.