contains 5 bonded and 1 nonbonded electron domains, giving an octahedral e-
domain geometry and a square pyramidal molecular geometry. (AX5
). For a molecule with an ideal square pyramidal molecular geometry, four of the five terminal atoms form a base by lying at the corners of an imaginary square planar unit, with the central atom located directly at the center of the square plane. The fifth terminal atom lies out of the plane of the other five atoms, at the apex (apical position) of the imaginary square pyramid. The actual molecular geometry is a distorted square pyramid where the atoms forming the base are puckered out of a plane in the direction towards the apical atom. This puckering occurs because the lone pair at the second apical position spreads out more in space than the bonded pair at the other apical position. The bond angles are compressed slightly from what would be observed in an ideal square pyramidal geometry for the same reason.
A cartoon model of the electron density of the lone pair of electrons, represented by a translucent purple spheroid, can be toggled on and off. Note that the shape of the spheroid does not represent the actual electron density of the lone pair, but the shape allow you to visualize how the presence of the lone pair dictates the molecular geometry.
Use your mouse (computer) or fingers (touch screen) to manipulate the Jmol model.