Rule 4 allows us to predict the position in which a lone pair will be found. For
example, the electron arrangement in an AX4E molecule or ion, such as IF4
, is
trigonal bipyramidal, but there are two different possible locations for the lone
pair. An axial lone pair lies on the axis of the molecule, where it strongly repels the
electron pairs in the three equatorial bonds, which lie at 90 angles to the axial
position; an equatorial lone pair lies on the molecule’s equator, on the plane perpendicular
to the molecular axis, where it strongly repels only the electron pairs in