So basically, we have the same molecules A on this side as on that side and the same number of B molecules on this side as on that side. We conclude that molecules tend to naturally move from a high concentration to a low concentration. So given situation A, we say that there exists a chemical concentration gradient and both molecules travel down their perspective, chemical concentrate their respective chemical concentration gradient. 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?