Question

C-3. Effective overlapping will be shows by:

• A. $\oplus\ominus + \oplus\ominus$
• B. $\oplus \atop \ominus$ + $\ominus \atop \oplus$
• C. $\oplus\ominus + \ominus\oplus$
• D. All the above

Answer 1

Answer: (A)

A

Answer 2

Effective overlapping occurs when atomic orbital lobes of the same phase overlap, leading to constructive interference and bond formation.

• (A) $\oplus\ominus + \oplus\ominus$: This represents two p-orbitals where same-phase lobes can overlap (e.g., $\oplus$ with $\oplus$, and $\ominus$ with $\ominus$) for both sigma (head-on) and pi (sideways) bond formation. This is effective overlap.

• (B) $\oplus \atop \ominus$ + $\ominus \atop \oplus$: This represents sideways overlap where the upper $\oplus$ lobe of one orbital overlaps with the upper $\ominus$ lobe of the other, and similarly for the lower lobes. This is opposite-phase overlap, leading to destructive interference (antibonding orbital). This is not effective overlap.

• (C) $\oplus\ominus + \ominus\oplus$: This represents two p-orbitals where the phases are inverted in the second orbital relative to the first. Any head-on or sideways overlap will involve lobes of opposite phases ($\oplus$ with $\ominus$), leading to destructive interference (antibonding orbital). This is not effective overlap.

Thus, only (A) shows effective overlapping.