group 2

• physical properties

  giant metallic structure

  good electrical conductor

  high melting and boiling point
• reactivity?

  nuclear charge increases

  shielding increases

  atomic radius increases

  nuclear attraction increases

  EASIER TO LOSE THE 2 OUTER ELECTRONS SO REACTIVITY INCREASES (less energy required)
• reaction with water

  react vigorously with water to form metal oxides with ionic bonding (can be burned in air)
• reaction with water

  react with cold (room temp) water, to form metal hydroxides and hydrogen

  THE GROUP 2 METAL REDUCES THE HYDROGEN IN THE WATER TO FORM HYDROGEN GAS
• Hydroxides and water


  group 2 hydroxides dissolve in water forming alkaline solutions

  Ca(OH)2 --> Ca2+ + 2OH-
• SOLUBILITY AND ALKALINITY

  as you go down the group, solubility increases

  increased concentration of OH$\ ^-$ ions in water

  alkalinity therefore increases due to more dissolved OH$\ ^-$ ions
• Group 2 OXIDES with water


  react to form an alkaline solution of hydroxide ions
• COMMERCIAL/INDUSTRIAL USE

  Mg(OH)2 - used in indigestion tablets as an antacid - neutralises excess stomach acid safely

  Ca(OH)2 - used in agriculture to neutralise ACID SOIL - neutralises acid soil by reacting with acid substances in the soil
• THERMAL DECOMPOSITION


  breaking down of a chemical substance into at least two chemical substances
• Group 2 carbonates

  thermally decomposed to form solid metal hydroxide and carbon dioxide gas
• going down the group..

  it becomes increasingly difficult to thermally decompose group 2 carbonates going down the group, meaning thermal stability of griup 2 carbonates increases down the group