T Shape or Trigonal Pyramidal

[104922499 1F]

How can I tell the difference between trigonal pyramidal and t shape when looking at the Lewis structures?

[Joshua Xian 1D]

Trigonal pyramidal occurs when tetrahedral electronic geometry has a lone e- pair as one of its four regions of e- density. T shape occurs when a trigonal bipyramidal electronic geometry has lone e- pairs as two of its five regions of e- density or when an octahedral electronic geometry has lone e- pairs as three of its six regions of e- density.

[Meredith Steinberg 2E]

T shape structures have the VSEPR formula AX3E2, which means there are 2 lone pairs on the central atom. Trigonal pyramidal structures have the VSEPR formula AX3E, which means there's one lone pair on the central atom.

[104922499 1F]

thanks! That clears it up