Group 2

• Have two electrons in their outermost electron

  • highest energy sub-shell is the S sub shell
• Group 2 metals are reducing agents

  • they are oxidise to form a 2+ ion
  • they lose two electrons
• second ionisation energy is greater than the first as the second electron is removed from a charged ion

  • greater nuclear attraction
  • more energy required to overcome this
  • removed from a 1+ charge
• Mg and Sr

  Mg has a greater first ionisation energy than Sr as Mg:

  • smaller atomic radius
  • greater nuclear attraction
• reactivity increases down the group

  (stronger reducing agents down the group)

  • atomic radius increases
  • more electrons so more shielding
  • less nuclear attraction between outermost electron and nucleus
  • less energy required to remove
• melting point

  decreases down the group

  • metallic bonds get weaker
  • increased size of ions leads to decreased electrostatic attraction
  • electron clouds do not bond as strongly
• Reactions with water (down the group)

  reactions become more vigorous down the group

  • faster reaction
  • higher pH
  • more vigorous fizzing
  • (ppt forms as you go up the group)
• reaction with oxygen


  metal + oxygen —> metal oxide

  • oxygen gets reduced
  • metal gets oxidised
• reaction with water

  metal + water —> metal hydroxide + hydrogen gas

  • metal is oxidised
  • oxygens oxidation number doesn’t change
  • hydrogen has been reduced
• reactions with dilute acids

  metal + acid —> salt + hydrogen gas

  • metal is oxidised
  • hydrogen is reduced

  down the group, sulphate become less soluble
• ionisation energy decreases down the group

  • increased nuclear attraction
  • increased atomic radius
  • increased shielding
• alkalinity increases down the group

  • higher pH
• group two oxides and water

  release OH- ions to form alkaline solutions of metal hydroxides

  E.g CaO + H2O —> Ca(OH)2
• test

  -add group 2 oxide to water

  -shake

  -measure pH of the metal hydroxide
• solubility of hydroxides in water increases down the group

  • increased concentration of OH- ions within a solution
• oxides, hydroxides and carbonates can be used to neutralise acids
• agriculture

  Calcium hydroxide increases the pH of acidic soils as lime

  • neutralises acid in soil forming neutral water
• medicine

  magnesium hydroxide is partially soluble in water

  • used in suspension to neutralise excess acid in stomach
  • treats acid indigestion
  • treats constipation