How the VSEPR Theory Allows Us to Determine the Most Favorable Molecule Geometries
VSEPR theory explains how atoms in a molecule are arranged in order to minimize valence electron repulsions. It describes the three-dimensional shape of a molecule and can predict the geometry of other molecules as well. This is a great tool to use when studying chemical reactions and understanding the structure of organic compounds.
Valence shell electron pair repulsion (VSEPR) is a theory that was developed by Ronald Gillespie and Ronald Nyholm. The idea is that the repulsion of a pair of electrons will push as far as possible in three-dimensional space.
If this happens, the shape of the molecule will be trigonal planar, which is a geometric shape with a triangular base and eight sides. It is also called an octahedral shape. In this form, the angles are 180deg and 90deg.
However, a molecule can have more than one bond and still be an octahedral, for example, the lone pair of electrons that is placed in equatorial positions on the central atom is not the atom itself. Instead, it is surrounded by two other atoms that have a pair of electrons in their own bonds.
Another way to determine a molecule's geometries is to count the number of lone pairs of electrons that are present around the central atom. The total number of lone pairs of electrons in a molecule is a good predictor of the molecule's octahedral shape.
Another type of molecule that is trigonal is the beryllium molecule, BeF2. A BeF2 molecule has only two bonding electrons on the central beryllium atom.
