1.2.10

Reactivity of Alkaline Earth Metals

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Reactivity of Group 2 Metals

The reactivity of group 2 metals increases down the group. This can be illustrated by their reactions with oxygen, water, and dilute acids.

Illustrative background for Reaction with oxygenIllustrative background for Reaction with oxygen ?? "content

Reaction with oxygen

  • Group 2 elements react with oxygen in the air to form metal oxides, For example:
    • 2Mg + O2 → 2MgO
  • The elements react more readily with oxygen down the group because of the decrease in ionisation energies.
Illustrative background for Reaction with waterIllustrative background for Reaction with water ?? "content

Reaction with water

  • Group 2 metals react with water to form metal hydroxides. For example:
    • Mg + 2H2O → Mg(OH)2 + H2
  • Reactivity increases as you go down Group 2. This is because the lower elements have lower ionisation energies.
    • Beryllium is an exception. If beryllium were to lose two electrons it would be tiny and have a very high charge density. This would make it unstable and so beryllium doesn't react with water.
Illustrative background for Reaction with dilute acidsIllustrative background for Reaction with dilute acids ?? "content

Reaction with dilute acids

  • Group 2 metals react with dilute acids to produce a salt and hydrogen. For example:
    • Ca + H2SO4 → CaSO4 + H2
  • Reactivity increases down the group because of the decrease in ionisation energies.
  • The salts produced become less soluble as you go down the group.

Group 2 Oxides Reacting with Water

Group 2 oxides react with water to form metal hydroxides.

Illustrative background for Group 2 oxides and waterIllustrative background for Group 2 oxides and water ?? "content

Group 2 oxides and water

  • Group 2 oxides steadily react with water.
  • The reaction produces a metal hydroxide salt. The salt dissociates into metal ions and hydroxide ions, giving the solution an alkaline pH.
Illustrative background for Solubility down the groupIllustrative background for Solubility down the group ?? "content

Solubility down the group

  • Group 2 hydroxides become more soluble down the group.
  • This means that the solutions become more strongly alkaline the further down Group 2 you go.
Illustrative background for Exceptions to the ruleIllustrative background for Exceptions to the rule ?? "content

Exceptions to the rule

  • Beryllium oxide does not react with water.
  • Magnesium oxide reacts but very slowly.

Jump to other topics

1Principles of Science I

1.1Structure & Bonding

1.2Properties of Substances

1.3Cell Structure & Function

1.4Cell Specialisation

1.5Tissue Structure & Function

1.6Working with Waves

1.7Waves in Communication

2Practical Scientific Procedures and Techniques

3Science Investigation Skills

4Principles of Science II

4.1Extracting Elements

4.2Relating Properties to use of Substances

4.3Organic Chemistry

4.4Energy Changes in Industry

4.5The Circulatory System

4.6Ventilation & Gas Exchange

4.7Urinary System

4.8Cell Transport

4.9Thermal Physics

4.10Materials

4.11Fluids

5Contemporary Issues in Science

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