GCSE Combined Science (AQA)

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Group 1: Reaction with Water

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Atomic structure and the periodic table The periodic table

Group 1: Reaction with Water

7:33 Reactions of Group 1 elements
Spec 4.1.2.5 4.1.2.1
Previous Group 1: Alkali Metals Next Group 1: Reaction with Oxygen
  • All alkaline metals react vigorously with water.
  • Cesium, the most reactive alkaline metal, reacts violently with water, producing a flame and potentially shattering the glass container.
  • Cesium has the chemical symbol Cs.
  • Reactivity increases down the group, making reactions with water more violent.
  • Alkaline metals reacting with water produce a metal hydroxide and hydrogen.
  • The general word equation: metal + water ��� metal hydroxide + hydrogen.
  • Example: Lithium + water ��� lithium hydroxide + hydrogen.
  • Metal hydroxides are bases and dissolve in water to form an alkaline solution.
  • Universal indicator in water changes color to show pH: green for neutral, purple for alkaline.
  • Lithium reacts with water, producing bubbles and moving on the surface.
  • Sodium reacts quickly with water, producing a yellow-orange flame and more rapid hydrogen bubbles.
  • Potassium reacts vigorously, producing a lilac flame and vigorous hydrogen bubbles.
  • The trend down the group can predict reactions: rubidium will bubble violently, and cesium will likely explode with water.
  • Balanced chemical equations for reactions with water:
  • Lithium: 2Li + 2H2O ��� 2LiOH + H2
  • Sodium: 2Na + 2H2O ��� 2NaOH + H2
  • Potassium: 2K + 2H2O ��� 2KOH + H2
  • Using data to predict reactions is a necessary skill for exams.

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