Trigonal planar

Definition

A trigonal planar molecular geometry occurs when a molecule has three atoms bonded to a central atom with no lone pairs, resulting in a flat, triangular shape. The bond angles are typically 120 degrees.

5 Must Know Facts For Your Next Test

1. In a trigonal planar geometry, the bond angle between the atoms is approximately 120 degrees.
2. This geometry is common for molecules with an AX3 type formula where 'A' is the central atom and 'X' are the surrounding atoms.
3. Examples of molecules with trigonal planar geometry include boron trifluoride (BF3) and formaldehyde (H2CO).
4. The absence of lone pairs on the central atom allows for equal repulsion between bonding pairs, maintaining a planar structure.
5. Trigonal planar molecular geometry results from sp2 hybridization of the central atom.

Review Questions

• What is the typical bond angle in a molecule with trigonal planar geometry?
• Which type of hybridization corresponds to trigonal planar molecular geometry?
• Give an example of a molecule that exhibits trigonal planar geometry.

Related terms

Bond Angle:

The angle formed between three atoms across at least two bonds.

sp2 Hybridization: A form of orbital hybridization in which one s orbital mixes with two p orbitals to form three equivalent sp2 hybrid orbitals arranged in a trigonal plane.

Molecular Geometry:

The three-dimensional arrangement of atoms within a molecule.