Use the remaining electrons to give lone pairs to the terminal atoms in order to satisfy the octet rule. Use any remaining electrons to give the central atom one or more lone pairs. Draw any resonance forms. True structure is the average of these forms. Resonance forms show the delocalization of charge .
Formal charge assumes equal sharing of electrons.
Oxidation state assumes transfer of electrons to the more electronegative atom. CO 2 Electron density isosurfaces of CO 2 . Electrostatic potential mapped onto 0.002 isosurface of CO 2 . Electrostatic potential map for BF 3 . This is a hypervalent compound.