Trigonal planar

Trigonal Planar is a term used in molecular geometry to describe the shape of molecules where a central atom is surrounded by three atoms or groups of atoms at the corners of an equilateral triangle. This geometric arrangement results from the sp² hybridization of the central atom, where one s orbital and two p orbitals mix to form three equivalent sp² hybrid orbitals. Each of these hybrid orbitals contains one electron and forms a sigma bond with the electron from the surrounding atoms or groups. The trigonal planar shape is characterized by bond angles of 120°, which minimizes the repulsion between the electrons in the bonding pairs according to the Valence Shell Electron Pair Repulsion (VSEPR) theory.

Characteristics

The trigonal planar molecular geometry is significant in chemistry because it determines various physical and chemical properties of the molecules, such as polarity, reactivity, and phases of matter. Molecules with a trigonal planar shape are usually nonpolar if all three atoms or groups attached to the central atom are identical. However, if one or more of the atoms or groups differ, the molecule can become polar due to an uneven distribution of charge.

Examples

Common examples of molecules with a trigonal planar geometry include Boron trifluoride (BF₃), Formaldehyde (CH₂O), and Ethylene (C₂H₄). In each case, the central atom (boron in BF₃, carbon in CH₂O and C₂H₄) is bonded to three other atoms, resulting in a flat, triangular shape.

Applications

The trigonal planar geometry plays a crucial role in various fields, including organic chemistry, material science, and pharmacology. For instance, the reactivity of ethylene in forming polymers is attributed to its trigonal planar structure, which facilitates the formation of pi bonds during polymerization reactions.

See Also

• Molecular geometry
• Hybridization (chemistry)
• Valence Shell Electron Pair Repulsion theory
• Sigma bond
• Polarity (chemistry)
• Organic chemistry
• Material science
• Pharmacology