Consider the following three triatomic species, each of which possesses a central atom surrounded by three electron domains but differing numbers of lone pairs.
• BF₃ (no lone pairs)
• SO₂ (one lone pair; S═O double bonds)
• O₃ (one lone pair; delocalized π bonding)
These molecules are often used to illustrate systematic variations in bond angles within trigonal planar electron-domain arrangements.
a. Rank the three species in order of increasing central-atom bond angle (smallest to largest).
b. Provide a numerical estimate (±2°) for each bond angle you listed in part (a).
c. Construct a comprehensive argument that accounts for the ranking in part (a). Your answer should compare (i) repulsion hierarchies involving lone pairs, (ii) the influence of π-bond electron density on domain repulsions, and (iii) any symmetry or resonance considerations that affect electron distribution.