Group 2

• Why do group 2 elements have a high melting point 


  They have a giant metallic structure with strong attractions between positive metal ions and delocalised electrons. These require a lot of energy to break
• Why do group 2 have a higher density than group 1


  Group 2 ions are smaller than group 1 ions so they can pack more closely
• Why are all group 2 elements reactive metals with similar chemical reactions?


  They all have 2 outer electron which they loose during reactions
• What is the appearance of group 2 compounds


  ionic, white cristalline solids
• atomic radius increases down group 2

  more shells of electrons so more shielding

  less nuclear attraction to the outer electrons
• first ionisation energy decreases down group 2


  more shells so more shielding

  weaker nuclear attraction to outer electron therefore more easily lost
• melting point decreases down group 2


  down group 2 the ions get larger so the attraction between the metal ion and the delocalised electrons decreases

  weaker metallic bond : lower melting point
• reactivity increases down group 2


  group 2 elements react by loosing their outer electrons

  • atomic radius increases
  • more shielding
  • weaker attraction between nucleus and outer electron so electrons lost more easily
• magnesium react with cold water

  • very slow reaction
  • a few bubbles

  Mg + 2H2O - Mg(OH)2 + H2
• magnesium reaction with steam


  • bright white light
  • white solid formed

  Mg + H2O - MgO + H2
• calcium react with cold water


  • effervescence
  • some white solid formed as some Ca(OH)2 did not dissolve

  Ca + 2H2O - Ca(OH)2 + H2
• strontium with cold water 


  • effervescence
  • solution of Sr(OH)2 forms

  Sr + 2H2O - Sr(OH)2 +H2
• barium with cold water


  • effervescence
  • colourless solution of Ba(OH)2 forms

  Ba + 2H2O - Ba(OH)2 + H2
• reactivity with water increases as you go down the group

  as you go down the group there are more shells and more shielding

  so a weaker nuclear attraction to electrons being lost
• change in oxidation number


  • metal is oxidised
  • hydrogen is reduced
• use of magnesium


  extraction of Ti from TiCl4
• both reactions of magnesium to produce titanium


  TiCl4 + 2Cl + 2C - TiCl4 + 2CO

  TiCl4 + 2Mg - Ti + 2MgCl2
• base and acid reaction


  M(OH)2 + acid - salt + H2O
• solubility of hydroxides 


  increases down the group
• PH of hydroxides

  increases down the group (more acidic)
• use of magnesium hydroxide in medicine

  indigestion remedies

  neutralises stomach acid
• calcium hydroxide in agriculture 


  neutralises acidic soil
• solubility of sulphates 


  decreases down the group
• confirming presence of Mg2+ ions


  take an unknown group 2 compound add NaOH

  sparingly soluble so a thick white precipitate would be seen
• confirming presence of Ba2+


  add sulfuric acid

  soluble so a colourless solution is formed
• uses of magnesium salts

  test for hydroxide ions
• Use of calcium compounds 


  Remove sulfate dioxide from a flur gas