Reactions of metals

Reactions with water

Metals can react with water, acid and oxygen. The reactivity of the metal determines which reactions the metal participates in.

When metals react with water, metal hydroxides and hydrogen gas are formed. This can be represented in different ways as shown:

Word equation

Calcium + water \to calcium\,hydroxide + hydrogen

Chemical equation

Ca + 2{H_2}O \to Ca(OH)_2^{} + H_2^{}

Ionic equation

Ca(s) + 2{H_2}O(l) \to Ca^{+2}(aq)+2OH^{-}(aq)

Reactions with acid

Metals above hydrogen on the electrochemical series react with acids

When metals react with acids, a salt of the metal and hydrogen gas are formed. The salt of the metal is named following the rules you learned in Unit 1 of the course.

Word equation

Magnesium + hydrochloric\,acid \to magnesium\,chloride + hydrogen

Chemical equation

Mg + 2HCl \to MgCl_2^{} + H_2^{}

Ionic equation

Mg(s) + 2H^{+}(aq)+2Cl^{-}(aq) \to Mg^{2+} (aq) +2Cl^{-}(aq)+H_{2}(g)

Reactions with oxygen

When metals react with oxygen, metal oxides are formed.

Word equation

Zinc + oxygen \to zinc(II)\,oxide

Chemical equation

2Zn + {O_2} \to 2ZnO

Ionic equation

2Zn(s) + {O_2}(g) \to 2Zn_{}^{2 + }O_{}^{2 - }(s)

Summary

The reactions of metals can be summed in the diagram below.

From very reactive to very unreactive, the metals run as follows: potassium, sodium, lithium, calcium, magnesium, aluminium, zinc, iron, tin, lead, copper, mercury, silver and gold. Potassium, sodium, lithium and calcium will react with water, acids and oxygen. Magnesium, aluminium, zinc, iron, tin and lead will not react with water, but will react with acids and with oxygen. Copper, mercury and silver will not react with water or acids, but will react with oxygen. Gold will not react with water, acids or oxygen.