As shown by computational chemistry , hypervalent molecules can only be stable given strongly polar ( and weakened ) bonds with electronegative ligands such as fluorine or oxygen to reduce the valence electron occupancy of the central atom to a maximum of 8 ( or 12 for transition metals ) .
As shown by computational chemistry , hypervalent molecules can only be stable given strongly polar ( and weakened ) bonds with electronegative ligands such as fluorine or oxygen to reduce the valence electron occupancy of the central atom to below 8 ( or 12 for transition metals ) .