As a domain expert in chemistry, I can explain the **Valence Shell Electron Pair Repulsion (VSEPR) theory**. This theory is a model used to predict the shapes of molecules. It was developed by the American chemist F. Albert Cotton in the 1960s. The VSEPR theory is based on the principle that electron pairs around a central atom will arrange themselves to minimize repulsion between them.

Here's how it works:


1. Determine the central atom: Identify the atom in the molecule that is bonded to the most other atoms.


2. Count the valence electrons: Add up the valence electrons of the central atom and all the atoms it is bonded to.


3. Determine the electron pair geometry: Divide the valence electrons into pairs. These pairs can be bonding pairs (shared between two atoms) or non-bonding pairs (lone pairs on the central atom).


4. Predict the molecular geometry: The arrangement of the electron pairs around the central atom will dictate the shape of the molecule. For example, if there are four bonding pairs, the electron pair geometry is tetrahedral, but if there is one lone pair, the molecular geometry will be trigonal pyramidal.


5. Consider the repulsions: Electron pairs will repel each other and spread out as much as possible. This repulsion is what influences the shape of the molecule.


6. Apply any exceptions: There are some exceptions to the theory, such as hypervalent molecules, which may not follow the standard rules.

The VSEPR theory is widely used in chemistry to predict the three-dimensional shapes of molecules, which are crucial for understanding their reactivity, polarity, and overall behavior.

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Valence shell electron pair repulsion (VSEPR) theory is a model used in chemistry to predict the geometry of individual molecules from the number of electron pairs surrounding their central atoms. It is also named the Gillespie-Nyholm theory after its two main developers, Ronald Gillespie and Ronald Nyholm.read more >>