During the electron transport chain which process leads to the production of large amounts of atp

The process by which energy from electron transport chain is used to make ATP is called oxidative phosphorylation.

Electrons flow from carriers with more negative reduction potentials to those with more positive potentials and eventually combine with oxygen and hydrogen to form water.

The difference in reduction potentials specifically between oxygen and NADH, an electron donor is quite large, about 1.14 volts and makes possible the release of a great deal of energy.  Some of the liberated energy is trapped in the form of ATP.