Molecular Geometry Answer Key (CHEM 1405)

For each of the following molecules, draw the best Lewis structure. Then, identify the correct the molecular shape and bond angle.

Molecule	Lewis Diagram	Shape	Bond Angle
1. SeO₃		Trigonal planar	120^o
2. NH₃		Trigonal pyramidal	109.5^o (Actual bond angle is closer to about 107^o due to higher repulsion from lone pairs vs. bonded pairs)
3. NO₂^-		Bent	120^o (Actual bond angle is closer to about 119^o due to higher repulsion from lone pairs vs. bonded pairs)
4. SO₂		Bent	120^o (Actual bond angle is closer to about 119^o due to higher repulsion from lone pairs vs. bonded pairs)
5. SiH₄		Tetrahedral	109.5^o
6. H₂S		Bent	109.5^o (Actual bond angle is closer to about 104.5^o due to higher repulsion from lone pairs vs. bonded pairs)
7. CH₂O		Trigonal Planar	120^o
8. CO₂		Linear	180^o