Trigonal planar

Definition

Trigonal planar is a molecular geometry where a central atom is bonded to three other atoms, arranged in a flat, triangular shape with bond angles of approximately 120 degrees. This arrangement arises from the steric repulsion of electron pairs around the central atom and is commonly observed in molecules with sp2 hybridization, influencing their physical and chemical properties.

5 Must Know Facts For Your Next Test

1. Trigonal planar geometry results in a symmetrical arrangement of bonds, minimizing electron pair repulsion according to VSEPR theory.
2. Examples of trigonal planar molecules include boron trifluoride (BF3) and ethylene (C2H4), which exhibit this geometry due to sp2 hybridization.
3. In trigonal planar structures, the three substituents lie in the same plane, making it easier for spectroscopic techniques to analyze these molecules.
4. Molecules with trigonal planar geometry often display specific reactivity patterns due to their flat structure and bond angles, influencing their interaction with other compounds.
5. The bond angles in a trigonal planar molecule are ideally 120 degrees but can vary slightly due to differences in electronegativity and steric effects.

Review Questions

• How does VSEPR theory explain the trigonal planar molecular geometry?
  • VSEPR theory posits that electron pairs around a central atom will arrange themselves as far apart as possible to minimize repulsion. In a trigonal planar geometry, there are three bonding pairs of electrons that repel each other, resulting in a flat, triangular arrangement. This arrangement maximizes the distance between the bonds, leading to the characteristic bond angles of approximately 120 degrees.
• Compare and contrast trigonal planar geometry with tetrahedral geometry in terms of bond angles and hybridization.
  • Trigonal planar geometry involves sp2 hybridization with three bond pairs around a central atom, resulting in bond angles of approximately 120 degrees. In contrast, tetrahedral geometry arises from sp3 hybridization, where four bond pairs surround the central atom, leading to bond angles of about 109.5 degrees. The difference in hybridization affects both the shape and spatial arrangement of the atoms, impacting molecular interactions.
• Evaluate the significance of trigonal planar geometry in determining the reactivity of organic molecules.
  • Trigonal planar geometry plays a critical role in the reactivity of organic molecules by influencing how they interact with other compounds. The flat structure and specific bond angles allow for better overlap during reactions, such as nucleophilic attacks on electrophiles. Understanding this geometry helps predict reaction mechanisms and product formation in organic chemistry, especially in addition reactions involving alkenes and similar compounds.

Related terms

sp2 hybridization: A type of hybridization where one s orbital and two p orbitals combine to form three equivalent sp2 hybrid orbitals, commonly found in trigonal planar molecules.

bond angle: The angle formed between two bonds that originate from the same atom, critical for determining the molecular geometry.

VSEPR theory: Valence Shell Electron Pair Repulsion theory explains how the shape of a molecule is determined by the repulsion between electron pairs around a central atom.