Group 2

• They lose 2 electrons to form 2+ ions.
• The electron configurations of elements always end in "_s2".
• As you go down group 2:

  • atomic radius increases as more shells are added
  • ionisation energy decreases
  • reactivity increases
• The extra shells that are added as you go down the group will cause more shielding. This means that the outer electrons are further away from the nucleus (weaker attraction), meaning that less energy is required to remove the outer electron. This causes the reactivity to increase.
• The nuclear charge increases down group 2, but the shielding effect cancels out the increase in number of protons in the nucleus.
• Group 2 metal + water --> metal hydroxide + hydrogen.

  With water, the metals' reactivity increases down the group.
• Mg is a bit different. It slowly reacts with cold water, but it reacts vigorously with steam. Instead of producing magnesium hydroxide, it produces magnesium oxide.
• Group 2 metal + oxygen --> metal oxide
• Group 2 metals are white solids.
• Group 2 oxides react with water to form metal hydroxides which will dissociate into OH- ions.
• As you go down the group, solutions become more strongly alkaline as the hydroxides become more soluble.
• The metal oxides & hydroxides react with acids to form the same type of salt and water.
• Group 2 metals can neutralise acids. For example...

  • calcium hydroxide can be used to neutralise acidic soils
  • magnesium hydroxide can be used to neutralise excess stomach acid