1. A molecule with a trigonal-planar shape has no lone pairs on the central atom.
An example is BF₃ (see Figure 1).
2. A molecule with a bent shape and a trigonal-planar electron domain shape has one lone pair on the central atom.
An example is SO₂ (see Figure 2).
3. A molecule that has a trigonal-pyramidal shape has three atoms and one lone pair around the central atom.
An example is NH₃ (see Figure 3).
