Free Science Lessons: Reactivity of Metals

Objectives

• Construct a reactivity series using reactions between metals and water, and metals and acids.
• Describe reactions of metals in terms of electron transfer.

Key Concepts

Reactions of Group 1 Metals with Water

• Potassium: Vigorous reaction with water, produces potassium hydroxide (alkali) and hydrogen gas.
• Sodium: Less vigorous than potassium, forms sodium hydroxide and hydrogen gas.
• Lithium: Slowest reaction among the three, produces lithium hydroxide and hydrogen gas.
• General reaction: Metal + Water → Metal Hydroxide (Alkali) + Hydrogen Gas.

Reaction of Calcium with Water

• Produces calcium hydroxide and hydrogen gas.
• Reacts fairly rapidly, but slower than potassium, sodium, and lithium.

General Observations

• Reactivity decreases from potassium to lithium in reactions with water.
• Metals reacting with water at room temperature:
  • Potassium, Sodium, Lithium: React very rapidly.
  • Calcium: Reacts quite rapidly.
  • Magnesium, Zinc, Iron, Copper: No reaction.

Reactions of Metals with Dilute Acids

• Potassium, Sodium, Lithium: Not reacted with acids due to dangerous vigorous reactions.
• Calcium: Reacts extremely vigorously.
• Magnesium: Reacts rapidly.
• Zinc: Reacts quite rapidly but less than magnesium.
• Iron: Reacts slowly.
• Copper: Does not react.

Reactivity Series

• Order of reactivity with dilute acids:
  1. Calcium
  2. Magnesium
  3. Zinc
  4. Iron
  5. Copper
• Non-metals in the series: Carbon and hydrogen are included for their relevance in chemistry.

Electron Transfer in Metal Reactions

• Metal Reactions: Involve loss of electrons to form positive ions.
• Example: Potassium forms K+ by losing one electron.
• Reactivity Dependence: Ability to lose electrons and form positive ions.
  • Top of series (e.g., Potassium): Easily form positive ions.
  • Bottom of series (e.g., Copper): Less likely to form positive ions.

Additional Resources

• Questions and exercises on the reactivity series can be found in the revision workbook.

Summary

• You should now be able to construct a reactivity series from metal reactions with water and acids and understand electron transfer during metal reactions.