When only one pair of shared electrons is involved in a covalent bond, the linkage is called a single bond.

Here's why:

* Covalent bonds form when atoms share electrons to achieve a stable electron configuration.

* A single bond represents the sharing of one pair of electrons between two atoms.

* Double bonds involve sharing two pairs of electrons, and triple bonds involve sharing three pairs of electrons.

Let me know if you'd like to know more about different types of covalent bonds!