S-block Elements

• Group 1 elements


  • Less e- to remove than group 2
  • Require more energy to remove e-
  • Smaller atoms than group 2
• Increasing attraction between nucleus and outer e-

  Increases down group 1
• Group 1 elements


  • Li
  • Na
  • K
  • Rb
  • Cs
  • Fr
• Colours of group 1 elements


  • Colourless =Mg
  • Brick red = Ca
  • Crimson red = Sr
  • Apple green = Ba.
  • yellow/orange = Na
  • Lilac =K. Scarlet =
• Hydroxides


  Become more soluble upon descending group
• Sulfones


  Become less soluble upon descending group
• Thermal stability of carbonates and hydroxides

  Decreases as you descend group 2
• Decomposition of carbonates and hydroxides


  1. CO₂ + M₂O

  2. Ca(OH)₂ → CaO + H₂O
• Group 2 elements


  • Small, highly charged ions
  • Able to polarise the carbonate ion which is destabilised and breaks down
  • Magnesium ion has high charge density
• Group 2 elements are less reactive than group 1 elements
• Reactivity of group 1 metals with water

  Increases as you go down the group
• Reactions of group 1 metals with water


  • Li: Float, fizz, move
  • Na: Float, fizz, move
  • K: Float, fizz, move, melt, burn
• All group 2 nitrides are insoluble
• All group 2 carbonates are insoluble
• Reactions of group 2 elements with oxygen


  2 M + O₂ → 2 MO
• Reactions of group 2 elements

  • Ba + 2 HCl → BaCl₂ + H₂
  • Ba(OH)₂ + 2 HCl → BaCl₂ + 2 H₂O
• Reactivity of group 2 elements decreases down the group
• Mg(OH)₂ is less soluble than Ba(OH)₂
• To increase the speed of a Mg reaction

  1. Add acid

  2. Heat
• Group 2 elements react with oxygen to form simple oxides
• Reactivity of group 2 elements

  Increases as you descend the group
• Properties of group 2 hydroxides


  • Basic
  • React with water to form solutions
• Group 2 oxides dissolve in water to give alkaline solutions
• Group 2 oxides neutralise acids