VSEP Number

VSEP number of a molecule is the number that describes the shape of the molecule. We easily find this number by taking the sum of the Lone Pairs and Bond Pairs of the molecule. Various Shapes of molecules according to the VSEP number is tabulated below:

The various shape of the molecules are discussed in the article below,

Linear Shape of Molecule

The molecule in a linear shape is arranged in such a way that it has two valance shells and the bond pair in this arrangement are arranged in such a manner that their repulsion is minimum, this is achieved by taking the bond pair in opposite directions.

BeF₂ is an example of a Linear Shape Molecule.

Trigonal Planar Shape of Molecule

There are three molecules attached to the central atom in the Trigonal Planer molecule. The molecules in the trigonal planar structure are arranged in the form of an equilateral triangle which helps them to reduce the repulsion between the electron pairs of the atoms.

BF₃ is an example of a Trigonal Planar Shape Molecule.

Tetrahedral Shape of Molecule

There are four molecules attached to the central atom in the Tetrahedral molecule. The molecules in the tetrahedral structure are arranged in the form of a tetrahedron, which helps them to reduce the repulsion between the electron pairs of the atoms.

CH₄ is an example of a Tetrahedral Shape Molecule.

Trigonal Bipyramid Shape of Molecule

There are five molecules attached to the central atom in the Trigonal Bipyramid molecule. The molecules in the trigonal bipyramid structure are arranged in the form of a triangular pyramid, which helps them to reduce the repulsion between the electron pairs of the atoms.

PF₅ is an example of a Trigonal Bipyramid Shape Molecule.

Octahedral Shape of Molecule

In Octahedral shape, the central atom attaches 6 different atoms i.e. in total there are 6 bond pairs. These 6 bond pairs and the central atom arrange Octahedral to minimize electron repulsion.

An example of an Octahedral Shape is SF_6.

Pentagonal Bipyramidal Shape of Molecule

In Pentagonal Bipyramidal Shape, the central atom is attached to seven atoms at the corner to minimize the repulsion between the electron pairs. 

An example of a Pentagonal Bipyramidal Shape is IF_7.

VSEPR Theory tells us about the basic structure of the molecules based on the force of repulsion between lone pair and bond pair of electrons. It states that any molecule arranged in such a structure minimizes the repulsion between the lone pair and bond pair of the molecule.

Let’s learn more about VSEPR theory in detail, including its postulates, limitations, and examples.