Answer and Explanation:
Hydrogen ions in the thylakoid space form an electrochemical gradient because of the difference in the concentration of protons (H+) and the difference in the charge across the membrane that they create. This potential energy is stored as chemical energy in ATP through chemiosmosis. The hydrogen ions are allowed to pass through the thylakoid membrane through an embedded protein complex called ATP synthase. Energy from the electron fuels membrane pumps that actively move hydrogen ions against their concentration gradient from the stroma into the thylakoid space. The photon causes an electron in the chlorophyll to become excited.