Group 2

• Group 2 elements


  Alkaline earth metals
• Group 2 elements


  • Form +2 ions when they react
  • Have electron configuration ending in S2
• Atomic radius


  Increases as you go down the group
• First ionization energy


  Decreases as you go down the group
• Shielding


  Weakens the attraction between the nucleus and outer electrons as you go down the group
• Melting point


  Generally decreases as you go down the group
• Metallic bonding


  Positive metal ions and delocalized electrons
• Metallic bonding


  Weakens as the metal ion gets larger but the charge and number of delocalized electrons remain the same
• Reaction with water


  Forms metal hydroxides and hydrogen gas
• Barium does not react with water
• Magnesium reacts slowly with cold water but more vigorously with steam, producing magnesium oxide instead of a hydroxide
• Solubility of group 2 hydroxides and sulfates

  Opposite trends as you go down the group
• Test for sulfates


  Add hydrochloric acid to remove carbonates, then add barium chloride to form a white precipitate of barium sulfate
• Neutralization


  Group 2 compounds can be used to neutralize acidic soils or excess stomach acid
• Barium meals


  • Barium sulfate suspension used to image the digestive tract in X-rays
• Extraction of titanium


  Titanium ore is converted to titanium chloride, then reduced using magnesium to produce pure titanium
• Removal of sulfur dioxide


  Calcium carbonate or oxide is sprayed onto the gas to form calcium sulfate, which can be used to make plasterboard