Others have mentioned that the teacher is correct, and that "chemical force" is an actual term to describe physical properties of things. I just wanted to touch on the subject of membranes in cells. Substances can enter our cells either through active or passive means. Ions diffusing by osmosis is a form of passive transport, which means no energy in the form of ATP is required for transport. Ions are able to pass the membrane freely because of their size and chemical properties your teacher discussed. Larger molecules, such as lipids or proteins, require active transport methods that use special proteins in the membrane that use up ATP.

This is why our nerves work so quickly, the cascading signal of ions happens almost instantly! It is a chain of differing electrical potentials caused by ion gradients.