Activity Series of Metals: Predicting Reactivity

The activity series of metals is an empirical tool used to predict products in displacement reactions and reactivity of metals with water and acids in replacement reactions and ore extraction. It can be used to predict the products in similar reactions involving a different metal.

Exploring the Activity Series Chart

The activity series is a chart of metals listed in order of declining relative reactivity. The top metals are more reactive than the metals on the bottom. For example, both magnesium and zinc can react with hydrogen ions to displace H₂ from a solution by the reactions:

Mg(s) + 2 H⁺(aq) → H₂(g) + Mg²⁺(aq)

Zn(s) + 2 H⁺(aq) → H₂(g) + Zn²⁺(aq)

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Reactivity Series Definition in Chemistry

By Anne Marie Helmenstine, Ph.D.

Both metals react with the hydrogen ions, but magnesium metal can also displace zinc ions in solution by the reaction:

Mg(s) + Zn²⁺ → Zn(s) + Mg²⁺

This shows magnesium is more reactive than zinc and both metals are more reactive than hydrogen. This third displacement reaction can be used for any metal that appears lower than itself on the table. The further apart the two metals appear, the more vigorous the reaction. Adding a metal like copper to zinc ions will not displace the zinc since copper appears lower than zinc on the table.

The first five elements are highly reactive metals that will react with cold water, hot water, and steam to form hydrogen gas and hydroxides.

The next four metals (magnesium through chromium) are active metals that will react with hot water or steam to form their oxides and hydrogen gas. All the oxides of these two groups of metals will resist reduction by H₂ gas.

The six metals from iron to lead will replace hydrogen from hydrochloric, sulfuric and nitric acids. Their oxides can be reduced by heating with hydrogen gas, carbon, and carbon monoxide.

All the metals from lithium to copper will combine readily with oxygen to form their oxides. The last five metals are found free in nature with little oxides. Their oxides form through alternate pathways and will readily decompose with heat.

The series chart below works remarkably well for reactions that occur at or near room temperatures and in aqueous solutions.

Activity Series of Metals

Sources

• Greenwood, Norman N.; Earnshaw, Alan (1984). Chemistry of the Elements. Oxford: Pergamon Press. pp. 82–87. ISBN 0-08-022057-6.