VSEPR (Valence Shell Electron Pair Repulsion) theory proposes that the geometric arrangement of terminal atoms, or groups of atoms about a central atom in a covalent compound, or charged ion, is determined solely by the repulsions between electron pairs present in the valence shell of the central atom. The number of electron pairs around the central atom can be determined by writing the Lewis structure for the molecule. The geometry of the molecule depends on the number of bonding groups (pairs of electrons) and the number of nonbonding electrons on the central atom. The five important electron-pair geometries were: When the central atom has 3 bonding pairs of electron the geometry is trigonal planar. The bond angles are all 120Ü.| | When the central atom has 4 bonding pairs of electron the geometry is tetrahedral. All of the bond angles are 109.5Ü.| | When the central atom has 5 bonding pairs of electrons and no non-bonding pairs the geometry is trigonal bipyramidal. Notice those atoms in the trigonal plane are referred to as equitorial atoms, while the atoms perpendicular to the trigonal plane are called axial atoms.| | When the central atom has 6 bonding pairs of electron the geometry is octahedral. All the bond angles are 90Ü.| |
Table of Geometry Molecule
Molecular geometry is based on the arrangement of atoms in a molecule and does not consider the non bonding electrons. A simple way to think of molecular bonding is to consider that the atoms in the molecule are exchanging electrons in order to complete their outer shells. Some atoms may give up a few electrons and others may accept a few electrons to result in their outer shell being filled and thus achieve a more stable configuration. The Geometrical patterns and examples corresponding to those predicted molecule is listed in the...