Group 2

• Group 2 hydroxides increase in solubility down the group as the ionic radius increases
• Group 2 forms M(OH)2 with water

  M2+ + 2OH- -> M(OH)2
• Mg(OH)2 is sparingly soluble. It is used as an antacid/to neutralise stomach acid
• Group 2 forms MSO4

  M2+ + SO42- -> MSO4
• The solubility of group 2 sulphates decreases down the group
• Group 2 hydroxides increase in solubility down the group
• BaSO4 is used as a contrast agent in x-rays. It is highly toxic but it is so insoluble that it cannot be absorbed into the bloodstream, so it is not harmful to patients
• BaSO4- white precipitate

  Mg(OH)2- white precipitate
• Ca(OH)2- used to neutralise soil in agriculture
• Flue gas desulphurisation- CaO or CaCO3 react with acidic fumes to produce CaSO4 (gypsum)
• Extraction of titanium


  Mg + TiCl4 -> 2MgCl2 + Ti

  This is a redox reaction - Mg is a reducing agent as it is oxidised
• Atomic radius increases as you go down Group 2.

  • This is because each extra electron shell is further away.
  • Ionisation energy decreases as you go down Group 2.
  • This is because the outer electrons are further away and experience less attraction to the nucleus.
• Melting points decrease as you go down Group 2.

  • This is because the ion cores have larger radii down the group.
  • The free electrons experience less attraction to the nuclei because of the larger radii.
  • The bonding is weaker, so the melting point is lower.
  • Magnesium has an anomalously low melting point.
  • This is because it has a different crystal structure to the rest of Group 2.