contains 4 bonded and 1 nonbonded electron domains, giving a trigonal bipyramidal e-
domain geometry and a see-saw molecular geometry. (AX4
). There is less electrostatic repulsion between the lone pair and the bonded electron domains when the lone pair is in the equatorial position as compared to the repulsion that would be present if in an axial position.
bond angles (~115° and 88.5°) are compressed slightly from the values observed in a molecule with both trigonal bipyramidal electron-domain and molecular geometries (120° and 90°) due to the lone pair spreading out more in space than the bonded pairs, compressing the bond angles.
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.