VSEPR is used together with Lewis structures to determine the shapes of molecules. The Lewis structure gives you the number of bonding electron pairs and lone pairs that surround a molecule's central atom. ... The repulsion between valence electron pairs on the central atom determines the shape of the molecule.

How is the VSEPR theory used?

VSEPR theory is used to predict the arrangement of electron pairs around central atoms in molecules, especially simple and symmetric molecules. A central atom is defined in this theory as an atom which is bonded to two or more other atoms, while a terminal atom is bonded to only one other atom.

What is VSEPR used to determine?

The valence shell electron pair repulsion (VSEPR) theory is a model used to predict 3-D molecular geometry based on the number of valence shell electron bond pairs among the atoms in a molecule or ion. This model assumes that electron pairs will arrange themselves to minimize repulsion effects from one another.