Which types of orbital overlap occur between two adjacent atoms to form a $doublebond$?

• A. Two $\sigma$ bonds from head-on overlap
• B. One $\sigma$ bond from head-on overlap and one $\pi$ bond from side-by-side overlap
• C. One $\sigma$ bond and two $\pi$ bonds
• D. Two $\pi$ bonds from side-by-side overlap

Answer: (B)

Verified step by step guidance

1. Recall that a double bond between two atoms consists of two types of covalent bonds: one sigma (\sigma) bond and one pi (\pi) bond.
2. Understand that a sigma (\sigma) bond is formed by the head-on (end-to-end) overlap of atomic orbitals along the internuclear axis. This overlap allows electron density to be concentrated directly between the two nuclei.
3. Recognize that a pi (\pi) bond is formed by the side-by-side (lateral) overlap of p orbitals that are oriented parallel to each other but perpendicular to the internuclear axis.
4. Combine these concepts to see that in a double bond, the first bond is a sigma (\sigma) bond formed by head-on overlap, and the second bond is a pi (\pi) bond formed by side-by-side overlap.
5. Therefore, the types of orbital overlap in a double bond are one sigma (\sigma) bond from head-on overlap and one pi (\pi) bond from side-by-side overlap.