CHEMISTRY · Single correct · AP · Chemistry · Compound Structure and Properties · Compound Structure and Properties
Problem
The thiocyanate ion, SCN−, can be represented by two major resonance structures:
I. S=C=N− II. −S–C≡N
Based on these contributing structures, which statement correctly predicts the relative bond lengths in the resonance hybrid?
(a) The S–C bond is shorter than the C–N bond because sulfur can use its 3d orbitals to form an additional π bond.
(b) The S–C bond is shorter than the C–N bond because sulfur forms a partial double bond in every resonance structure.
(c) The C–N bond is shorter than the S–C bond because it has the higher average bond order.
(d) The S–C and C–N bonds are the same length because each appears as a double bond in at least one resonance contributor.