How many valence electrons occupy sigma-bond orbitals in a single covalent bond between two atoms?

• A. 2
• B. 0
• C. 4
• D. 1

Answer: (A)

Verified step by step guidance

1. Understand that a single covalent bond between two atoms is formed by the overlap of atomic orbitals, creating a sigma (\(\sigma\)) bond.
2. Recall that each atom contributes one electron to the bond, so the total number of electrons in the bond is the sum of these contributions.
3. Recognize that these electrons occupy the sigma-bond molecular orbital formed by the overlap, which is a bonding orbital.
4. Since each bond involves two electrons, the number of valence electrons occupying the sigma-bond orbital in a single covalent bond is 2.
5. Therefore, the correct answer corresponds to the number of electrons shared in the sigma bond, which is 2.