Remember that because the electron transport chain actually generates an electrochemical gradient for the protons, what that does is it creates a net positive charge on the outside portion of the inner membrane and a negative charge on the inner portion of the inner mitochondrial membrane. Now, ATP molecules have a greater charge than ADP molecules. ATP have a net charge of negative four, while ATP have a net charge of negative three. And so what that means is because the ATP have a greater negative charge, that greater negative charge on the ATP will promote the movement of these more negatively charged molecules onto the side of the membrane that contains a positive charge. And that's the side of plasmic side. So what that implies is the greater negative charge on the ATP molecules actually promotes the movement of these ATP across the inter mitochondrial membrane onto this intermembrane side because it's the side that contains a greater concentration of protons.