Trigonal planar

In chemistry, trigonal planar is a molecular geometry with one atom at the center and three atoms at the corners of a triangle all in one plane. In a trigonal planar molecule where all three attached atoms are identical, all bond angles will be 120° and the molecule will belong to point group D3h. Molecules where these atoms differ − such as H2CO − as well as more complex molecules − such as alkenes − will deviate from this ideal geometry due to lowered molecular symmetry. In general the atomic orbitals of a trigonal planar molecule are sp2 hybridized.

Examples of molecules with a trigonal planar geometry include boron trifluoride BF3, formaldehyde H2CO, and sulfur trioxide SO3. Some ions with trigonal planar geometry include the nitrate ion, NO3−, the carbonate ion, CO32−, and the borate ion, BO33−.

Pyramidalization is a distortion of this molecular shape towards a tetrahedral molecular geometry. One way to observe this distortion is in pyramidal alkenes.

Trigonal geometri