The O-S-O bond angle referenced is 120 degrees.
This specific angle is observed in molecules where a sulfur atom is bonded to two oxygen atoms, forming an O-S-O structure. Understanding bond angles helps predict molecular geometry, which in turn influences a molecule's properties.
Understanding the O-S-O Angle
According to the provided reference, the O-S-O bond angle discussed is 120 degrees.
Comparison to Other Molecules
The reference explicitly compares this angle to the bond angle in water (H₂O), where the O-H bond angle is approximately 104.5 degrees. While both molecules can adopt a bent geometry around the central atom, the O-S-O angle is significantly larger than the H-O-H angle in water.
Factors Influencing the Angle
The larger angle of 120 degrees, compared to water's 104.5 degrees, is attributed to increased electron repulsion. Specifically, the reference states:
"This is greater than the bent bond angle of 104.5 degrees in water (a similar molecule). This can be explained by the additional repulsion provided by the two S=O. bonds."
This indicates that the presence of double bonds between sulfur and oxygen (S=O bonds) contributes more significantly to electron repulsion than the single bonds and lone pairs in water. This increased repulsion forces the oxygen atoms further apart, resulting in a wider O-S-O angle.
Molecular Geometry Context
The O-S-O angle of 120 degrees is characteristic of certain molecular geometries. For example:
- In molecules like sulfur trioxide (SO₃), the sulfur atom is double-bonded to three oxygen atoms, forming a trigonal planar geometry. The O-S-O angles in SO₃ are all 120 degrees.
- While the reference compares the angle to water (which is bent), the 120-degree angle itself is often associated with trigonal planar electron group geometry, where the ideal bond angle is 120 degrees. The specific molecule being referenced likely features an O-S-O unit within a structure where this angle occurs. Sulfur dioxide (SO₂) has a bent shape, but its angle is closer to 119 degrees due to lone pair repulsion, though still relatively close to 120 degrees and significantly larger than water's angle. The reference's exact value points towards a specific context, possibly an idealized value or a structure where the 120 degree is precise.
Understanding these angles is crucial in chemistry for determining molecular shape and predicting properties like polarity.
