Advanced Topic 161 of 1102 Bonding & Molecular Structure
T-Shaped Geometry
Three bonds and two lone pairs on a trigonal bipyramid, as in ClF3.
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In-depth explanation of T-Shaped Geometry
T-shaped geometry arises when a central atom has five electron domains, three bonds and two lone pairs, in a trigonal bipyramidal arrangement. Both lone pairs occupy equatorial positions, where they have more room and experience fewer 90-degree repulsions, leaving the three bonded atoms in a T shape. The two axial bonds are collinear with the central atom, while the third bond is perpendicular to them. This geometry is typical of interhalogen compounds and some hypervalent species. The lone pairs distort the symmetry, so the molecule is polar.
Going deeper: T-Shaped Geometry
Key ideas: AX3E2: ClF3 (angles about 87.5 degrees between axial and equatorial atoms), BrF3, ICl3 (dimer in solid). Two lone pairs go equatorial with 120 degrees between them, so the three atoms are one equatorial and two axial. Axial bonds are longer than the equatorial bond, and the F-Cl-F angle is a little less than 90 degrees.
Common mistakes and connections: Students mix this up with trigonal planar (three atoms) or give 90 degrees exactly. Another error is assuming a T-shape is nonpolar due to the linear axial pair, but the third bond and the lone pairs break symmetry. Links to the family of five-domain shapes, interhalogens and hypervalency.
Visualization of T-Shaped Geometry
Two equatorial lone pairs on chlorine in ClF3 leave three fluorines in a T shape, with F-Cl-F angles slightly under 90 degrees. The interactive lesson shows this as a live animation or chart.
Worked example and use case
Chlorine trifluoride, ClF3, is T-shaped with two lone pairs on chlorine and is polar.
Frequently asked questions about T-Shaped Geometry
What is T-Shaped Geometry?
Three bonds and two lone pairs on a trigonal bipyramid, as in ClF3.
Is T-Shaped Geometry a beginner, intermediate or advanced topic?
T-Shaped Geometry is a advanced topic in Bonding & Molecular Structure. It builds on beginner and intermediate topics, so review those first if needed.
What should I learn before T-Shaped Geometry?
Study these earlier topics in Bonding & Molecular Structure first: Bent Geometry, Trigonal Pyramidal Geometry, See-Saw Geometry.
What comes after T-Shaped Geometry?
The next topics in Bonding & Molecular Structure are Square Planar Geometry and Square Pyramidal Geometry.
Can I practise T-Shaped Geometry with quizzes?
Yes. The interactive lesson includes a self-check question on T-Shaped Geometry, and the Bonding & Molecular Structure quiz draws on every topic in this area.
Where T-Shaped Geometry fits in Bonding & Molecular Structure
T-Shaped Geometry is topic 46 of 104 in Bonding & Molecular Structure.