Place the following events of the electron transport chain in order. Rank the items from the event that occurs first to the event that occurs last.

The correct order of events in the electron transport chain is as follows:

1. Oxidation of NADH
   • NADH donates high-energy electrons to Complex I of the electron transport chain, becoming oxidized to NAD+^++.
2. Electrons enter the electron transport chain
   • Electrons are transferred through a series of protein complexes and carriers in the inner mitochondrial membrane.
3. Release of energy for ATP synthesis
   • As electrons move through the chain, energy is released, which is used to pump protons across the mitochondrial membrane, creating a proton gradient that powers ATP synthesis via ATP synthase.
4. Electrons leave the electron transport chain
   • Electrons are ultimately passed to oxygen at the end of the chain.
5. Reduction of oxygen and formation of water
   • Oxygen, the final electron acceptor, combines with electrons and protons to form water.