Electromotive series, also called the electrochemical series or activity series, is a listing of metals and hydrogen with respect to their tendency to lose electrons during chemical reactions. Metals that lose electrons more readily than hydrogen does are listed in the series before hydrogen. Those that lose electrons less readily than hydrogen follow hydrogen in the listing. The following is the order of some commonly used elements in the electromotive series: potassium, calcium, sodium, magnesium, aluminum, zinc, iron, nickel, tin, lead, hydrogen, copper, mercury, silver, platinum, gold.