Each reaction in the activity series is an oxidation half-reaction.

• Each reaction in the activity series is an oxidation half-reaction.
• The half-reactions at the top are most likely to occur in the forward direction.
• The half-reactions at the bottom are most likely to occur in the reverse direction.
• If we pair a half-reaction from the top of the list with the reverse of a half-reaction from the bottom of the list, we get a spontaneous reaction.