Group 2

• Chemical trends 


  Going down the group the metals become more reactive .

  • increased shielding effect and a larger distance between the outer most electrons and nucleus.
  • The elements become more reactive as it gets easier for the atoms to lose two electrons and become 2+ ions
• Group 2 hydroxides 


  Going down the group, the solutions formed from the reaction of group 2 oxides with water become more alkaline.

  O2- (aq) + H2O (l) → 2OH- (aq)

  the higher the concentration of OH- ions formed, the more alkaline the solution.

  • going down the group, the solubility of the hydroxides increases .
  • the concentration of OH- ions increases, increasing the pH of the solution.
• What is the trend going down the group for the solubility of group 2 hydroxides ?

  Going down the group, the solubility of the hydroxides increases . Which means that the solution formed from the reactions of the group 2 metal Oxides and water become more alkaline going down the group.
• trend for group 2 sulfates

  The solubility of the group 2 sulfates decreases going down the group
• What does group 2 elements react with?

  Oxygen, water and dilute acids
• Group 2 metals reactions with oxygen

  2Mg(s) + O2 (g) —> 2MgO(s)

  2Ca(s) + O2 (g) —> 2CaO(s)

  2Sr(s) + O2(g) —> 2SrO(s)

  Sr(s) + O2(g) —> SrO2(s)

  2Ba(s) + O2(g) —> 2BaO(s )

  Ba(s) + O2(g) —> BaO2(s)
• Melting point

  • the size of the cation increases down the group
  • therfore the strength of the metallic bonds decreases down the group
  • therefore the melting point decreases
• What element does not follow the trend of melting point down group 2 ?

  Magnesium