The thiosulfate ion, S₂O₃²⁻, contains two sulfur atoms in different oxidation states and is widely used as a photographic fixer.
Answer the following, supporting all claims with clearly labeled Lewis representations when requested.
(a) Compute the total number of valence electrons that must be shown in a complete Lewis structure of S₂O₃²⁻.
(b) Multiple skeletal arrangements are possible for the two sulfur atoms (e.g., S–S central chain or one sulfur in the center with the other terminal). Choose the arrangement that leads to the lowest overall formal charge magnitude and draw all corresponding resonance structures.
(c) For one of your resonance structures, assign formal charges to every atom and state the oxidation number of each sulfur atom. Show how the two sulfur atoms occupy different oxidation states in the same ion.
(d) Based on your resonance set, predict which S–O bond (if any) is expected to be longest. Justify your prediction using bond order arguments derived from the resonance structures.