Enter the total number of valence electrons and the number of non-bonding electrons into the calculator to determine the molecular geometry.

Vsepr Theory Formula

The following formula is used to calculate the molecular geometry using VSEPR (Valence Shell Electron Pair Repulsion) Theory.

MG = V - N

Variables:

  • MG is the molecular geometry
  • V is the total number of valence electrons
  • N is the number of non-bonding (lone pair) electrons

To calculate the molecular geometry, subtract the number of non-bonding (lone pair) electrons from the total number of valence electrons. The result will give you the molecular geometry according to the VSEPR Theory. Note: This is a simplified version of the VSEPR Theory. The actual calculation of molecular geometry using VSEPR Theory involves more complex considerations, including the types of bonds (single, double, triple) and the presence of any unpaired electrons.

What is a Vsepr Theory?

VSEPR (Valence Shell Electron Pair Repulsion) Theory is a model used in chemistry to predict the geometry of individual molecules based on the number of electron pairs surrounding their central atoms. It postulates that these electron pairs, including both bonding and lone pairs, will arrange themselves in three-dimensional space to minimize their mutual repulsion, thus determining the shape of the molecule.

How to Calculate Vsepr Theory?

The following steps outline how to calculate the Molecular Geometry using the VSEPR Theory.


  1. First, determine the total number of valence electrons (V).
  2. Next, determine the number of non-bonding (lone pair) electrons (N).
  3. Next, use the formula MG = V – N to calculate the Molecular Geometry.
  4. Finally, determine the Molecular Geometry based on the calculated value.
  5. After inserting the variables and calculating the result, check your answer with the reference materials or a reliable source.

Example Problem:

Use the following variables as an example problem to test your knowledge.

Total number of valence electrons (V) = 20

Number of non-bonding (lone pair) electrons (N) = 4