A single covalent bond between two atoms is associated with two electrons.

Here's why:

* Covalent bond: A covalent bond forms when two atoms share electrons.

* Single bond: A single bond means that one pair of electrons is shared.

* Electron pair: A pair of electrons is needed to form a bond, with one electron coming from each of the participating atoms.

Therefore, two electrons are involved in the formation of a single covalent bond.