Molecule A travels from the left side, where we have a high concentration, to the right side, where we have a low concentration and molecule B moves in the opposite from a high concentration the right side to the left side, where we have a low concentration. And this is known as the chemical concentration gradient or simply our concentration gradient. Now, what about the electrical gradient? Well, in this case, molecule A and molecule B were both neutral. They had no charge. Suppose our molecules now have a charge.