T-shape

[Shannee Mak 3F]

Can someone briefly explain the t-shape to me?

And why the two lone pairs would be next to each other in this shape?

Thanks

[Hellen Truong 2J]

One example of T-shape is AX3E2, which has a structure of trigonal bipyramidal, so the lone pairs always go on the equatorial plane because they are separated from the bonded atoms by 90 and 120 degrees. If the lone pairs went on the axial plane, it would only be separated by 90 degrees which is unstable since lone pairs don't have any positive nucleus and have a lot of repulsion. Therefore, the 2 axial atoms and the 1 equatorial atom form a T-shape.

[Leah Savage 2F]

The T-shape shows up twice, once for a molecule with shape AX3E2, and once for a molecule with shape AX3E3. Both times the axial plane is made up of atoms, and the equatorial plane includes one equatorial atom and one or two lone pairs. This creates a t-shape for both, since the 2 axial and 1 equatorial atoms make up a t-shape.