Reactions of Period 3 & Period 4 Metals with Acids and Water

Introduction to Period 3 & Period 4 Metals

In the periodic table, Period 3 includes metals like sodium (Na), magnesium (Mg), and aluminum (Al), while Period 4 includes potassium (K) and calcium (Ca). Understanding how these metals react with acids and water is essential in chemistry.

Reactions with Acids

• Sodium (Na): Reacts vigorously with acids, producing hydrogen gas and a salt. For example, with hydrochloric acid (HCl):

$$\text{2Na} + \text{2HCl} \rightarrow \text{2NaCl} + \text{H}_2$$

• Magnesium (Mg): Reacts steadily with acids, also producing hydrogen gas and a salt. For example, with sulfuric acid (H₂SO₄):

$$\text{Mg} + \text{H}_2\text{SO}_4 \rightarrow \text{MgSO}_4 + \text{H}_2$$

• Aluminum (Al): Reacts with acids to produce hydrogen gas and a salt, but the reaction may initially be slow due to the protective oxide layer on aluminum. For example, with hydrochloric acid:

$$\text{2Al} + \text{6HCl} \rightarrow \text{2AlCl}_3 + \text{3H}_2$$

• Potassium (K): Reacts explosively with acids, producing hydrogen gas and a salt. For example, with hydrochloric acid:

$$\text{2K} + \text{2HCl} \rightarrow \text{2KCl} + \text{H}_2$$

• Calcium (Ca): Reacts readily with acids, producing hydrogen gas and a salt. For example, with hydrochloric acid:

$$\text{Ca} + \text{2HCl} \rightarrow \text{CaCl}_2 + \text{H}_2$$

Reactions with Water

• Sodium (Na): Reacts vigorously with water, producing sodium hydroxide and hydrogen gas:

$$\text{2Na} + \text{2H}_2\text{O} \rightarrow \text{2NaOH} + \text{H}_2$$

• Magnesium (Mg): Reacts slowly with cold water but more rapidly with steam, producing magnesium hydroxide and hydrogen gas:

$$\text{Mg} + \text{2H}_2\text{O} \rightarrow \text{Mg(OH)}_2 + \text{H}_2$$

• Aluminum (Al): Does not react with water due to its protective oxide layer, but reacts with steam to produce aluminum oxide and hydrogen gas:

$$\text{2Al} + \text{3H}_2\text{O} \rightarrow \text{Al}_2\text{O}_3 + \text{3H}_2$$

• Potassium (K): Reacts very vigorously with water, producing potassium hydroxide and hydrogen gas:

$$\text{2K} + \text{2H}_2\text{O} \rightarrow \text{2KOH} + \text{H}_2$$

• Calcium (Ca): Reacts with water to produce calcium hydroxide and hydrogen gas:

$$\text{Ca} + \text{2H}_2\text{O} \rightarrow \text{Ca(OH)}_2 + \text{H}_2$$