4.3 - Properties of Group 1 Compounds

• hydroxides


  white solids

  strong bases

  solubility increases down group 1
• Carbonates


  all white

  solutions are alkaline because carbonate ions remove H+ ions to form hydrogencarbonate ions & hydroxide ions

  very soluble -solubility increases down the group
• decomposition of group 1 carbonates

  most don't decompose on heating exept lithium carbonate
• general formula of group 1 carbonates

  M2CO3
• nitrates


  white crystalline solids

  very soluble in water
• general formula of group 1 nitrates

  MNO3
• decomposition of group 1 nitrates

  lithium nitrate decomposes in to the oxide, nitrogen dioxide & oxygen

  sodium & potassium nitrate only decompose as far as the nitrite
• why sodium and potassium compounds are used as chemical reagents

  ions are unreactive so act as spectator ions

  most are soluble in water including hydroxides & carbonates

  ions are colourless in aqueous solutions so don't hide or interfere with colour changes
• group 1 hydrides


  white crystalline solids with metal ions of hydride ions
• why are group 1 hydrides called saline hydrides

  they have the same crystal structure as sodium chloride
• how are group 1 hydrides supplied

  as suspensions in mineral oil because they can react violently with water or moist air
• preparing group 1 hydrides

  made by passing hydrogen gas over heated metal
• reaction of hydrides with water

  XH + H2O → XOH + H2
• heating hydrides


  decompose back into the metal and hydrogen
• electrolysis of lithium hydride

  metal is released at Cathode

  hydrogen is given off at anode