The ABE3 molecule geometry is classified as trigonal pyramidal. In this notation, ‘A’ represents a central atom, ‘B’ represents bonded atoms, and ‘E’ denotes lone pair electrons. In the case of ABE3, the central atom is bonded to three other atoms, with one lone pair of electrons on the central atom.
The presence of the lone pair pushes the bonded atoms closer together, resulting in a geometry that is not flat, like a trigonal planar shape, but instead takes on a three-dimensional pyramid shape. The bond angles in a trigonal pyramidal molecule are typically less than 109.5 degrees, which is slightly compressed from the ideal tetrahedral angle due to the lone pair of electrons occupying more space than the bonding pairs.
Common examples of molecules with ABE3 geometry include ammonia (NH3), where nitrogen is the central atom with three hydrogen atoms bonded to it and one lone pair of electrons.