Final answer:
In a single covalent bond, one pair of electrons (two electrons) is shared; in a double bond, two pairs (four electrons) are shared; and in a triple bond, three pairs (six electrons) are shared.
Step-by-step explanation:
The number of electron pairs shared in covalent bonds varies depending on whether the bond is a single, double, or triple bond. In a single covalent bond, such as the one found in hydrogen gas (H-H), two atoms share one pair of electrons. This means that a total of two electrons are shared in a single bond. For a double covalent bond, atoms share two pairs of electrons, resulting in a total of four electrons being shared. A familiar example is the oxygen molecule (O=O), where each oxygen atom shares two of its electrons with the other. Lastly, a triple covalent bond involves the sharing of three pairs of electrons, which means a total of six electrons are shared between the two atoms, as observed in nitrogen gas (N≡N), where two nitrogen atoms share three pairs of electrons.