What do equipotential lines represent in an electric field?

Equipotential lines are like contour lines on a map which trace lines of equal altitude. In this case the "altitude" is electric potential or voltage. Equipotential lines are always perpendicular to the electric field. In three dimensions, the lines form equipotential surfaces.

Both models are effective because they show the valence electrons, and these valence electrons indicate the reactivity of an element.