AXE notation

AXE notation is a type of notation used in chemistry to write shapes of molecules. Instead of showing specific chemical elements, it uses other letters as placeholders: A for the atom in the middle, X for any other atoms bonded to it, and E for any lone pairs. VSEPR theory can use this to predict the shape of a molecule.

AXE notation does not represent multiple bonds: both ammonia and thionyl chloride are  molecules with trigonal pyramidal molecular geometry, even though thionyl chloride has a double bond.

 Kepert model 
The Kepert model is used when the middle atom is a transition metal. Lone pairs on transition metals don't normally effect the shape of the coordination complex, so these shapes are written in terms of M for metal and L for ligand.

Category:Molecular geometries