Formaldehyde :Trigonal Planar Molecular Geometry

In this example, H₂CO, the Lewis diagram shows carbon at the center with no lone electron pairs. The carbon and and the oxygen are bonded through a double bond which counts as "one electron pair". Hence the molecule has three electron pairs and is trigonal planar. Formaldehyde is the simplest member of a class of organic compounds called aldehydes. These compounds have the structural component of the carbon double bond oxygen and at least one hydrogen atom and are always in the trigonal planar format geometry.

Formaldehyde or methanal is a water soluble gas. A 37% solution is water, known as formalin, is a biological preservative and in used in embalming fluids.