Group 2

The Group 2 Elements

  • Also known as the 'alkaline earth metals'
  • These are metallic elements in the s-block of the Periodic Table
  • Group 2 atoms have an outer shell s2 electron configuration, and tend to lose 2 electrons when they react
  • Their compounds are white solids forming colourless solutions if soluble
  • The elements are light metals with low densities and have high melting points due to strong metallic bonding and a giant metallic structure. The strength of the metallic bond decreases down the group.
  • Increase in reactivity down the group - decrease in attraction between outer electrons and the nucleus.
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Group 2 Elements With Oxygen

  • These are vigorous reactions releasing energy in the form of heat
  • The reactions become more violent down the groupas the reactivity of the metals increases.
  • The group 2 metal oxides formed have a giant ionic lattice structure and high melting point
  • Group 2 metals form 2+ ions and oxygen forms 2- ions
  • The metal is the reducing agent and undergoes oxidation
  • Oxygen is the oxidising agent and undergoes reduction
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Group 2 Elements With Water

  • Group 2 elements will react with water to form alkaline metal hydroxides and release H2 gas 
  • These reactions release energy in the form of heat. The reaction between the metal and water become more vigorous down the group as the reactivity of the metals increases.
  • The solid metal reacts with water to form a colourless solution and bubbles of colourless gas appear.
  • Mg is the least reactive and so only reacts rapidly with steam
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Group 2 Elements With Dilute Acids

  • Group 2 metals react with dilute acids to form a salt and hydrogen.
  • The reaction becomes more violent down the group as the reactivity of the metals increases.

e.g  Sr (s) + 2HCl (aq) --> SrCl2 (aq) + H2 (g)

The metal (Sr) loses electrons and is oxidised

H gains electrons and is reduced

Sr is the reducing agent

HCl is the oxidising agent

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Group 2 Oxides With Water

  • Oxides react with water to produce a solution of the metal hydroxide. This is an alkaline solution (i.e contains OH-)
  • The hydroxides dissolve only slightly in water, and when the solution becomes saturated, any further metal hydroxide is a solid precipitate
  • Solubility of the hydroxides increases down the group. The solution becomes correspondingly more alkaline.
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Uses of Group 2 Compounds

  • Ca(OH)2 is used by farmers and gardeners as lime to neutralise acidic soils.
  • Mg(OH)2 is used as 'milk of magnesia' to neutralise the stomach acid that causes indigestion. Calcium carbonate can also be used for this. Medicines like these are called antacids.
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