Group 2

• Atomic Radius

  Atomic radius increases down the group due to additional electron shells
• Reactivity

  Increased electron shielding down the group makes outer electrons easier to lose, therefore reactivity increases down the group
• Ionisation Energy

  The first IE decreases down the group due to greater atomic radius and increased shielding
• Melting Point

  The group 2 elements are metallic - the larger the ions within the metallic structure, the weaker the attractive forces so melting point decreases down the group
• Reactions with Water

  The group 2 metals react with water in a redox reaction to produce a metal hydroxide and hydrogen - the metal hydroxide forms an alkaline solution

  E.g. Mg + H2O --> Mg(OH)2 + H2
• Solubility of Hydroxides

  Solubility increases down the group meaning magnesium hydroxide (Mg(OH)2 is the least soluble and barium hydroxide (Ba(OH)2 is the most soluble

  Magnesium hydroxide is used in medicine as an antacid - indigestion relief (alkaline and can neutralise acids, also used in agriculture neutralise acidic soil)
• Solubility of Sulfates

  Group 2 sulfates decrease in solubility down the group meaning (MgSO4) is the most soluble and (BaSO4) is the least soluble - insolubility of barium sulfate is useful in medicine as barium meals (cannot be absorbed into blood)

  • Barium chloride is used as a test for sulfate ions as it reacts to form barium sulfate which forms a white ppt - Ba2+ + SO42- --> BaSO4(s)
• Metal Extraction

  Magnesium used in the extraction of titanium from titanium chloride via a displacement reaction: TiCl4 + 2Mg --> 2MgCl2 + Ti

  Why magnesium is reducing agent: Mg changes ox state from 0 to +2 so electrons are lost
• Flue Gas Removal

  Calcium oxide reacts with sulfur dioxide to remove it from from factory pollutants and prevent being released into the atmosphere forming calcium sulfite and water

  CaO + 2H2O + SO2 ---> CaSO3 + 2H2O
• Explain (structure and bonding) why magnesium chloride has a high melting point

  Giant ionic lattice, strong electrostatic forces between Mg2+ and Cl- ions
• Magnesium Reaction with Steam

  Observation: Bright/white light

  Equation: Mg(s) + H2O (g) ---> MgO (s) + H2 (g)
• State the observation when dilute NaOH is added to separate solutions of magnesium chloride and barium chloride

  MgCl2: White ppt

  BaCl2: No change
• Strontium Metal Extraction

  Strontium metal can be extracted by heating strontium oxide with aluminium metal

  Equation: 3SrO + 2Al ---> Al2O3 + 3sr

  Al acts as a reducing agent, Sr is collected as a vapour because Al2O3 is an ionic lattice so has strong ionic attractions than Sr which is a metallic structure with weaker bonding
• Reaction of Calcium with water at 25 degrees celsius and predict a pH of the solution formed

  Ca + 2H2O ---> Ca(OH)2 + H2

  pH: 8-12
• Which property would you expect the element radium, Ra, to possess?

  It is a good conductor of electricity
• Explain why the m.p of magnesium is higher than the m.p of sodium

  Mg2+ has a higher charge than Na which has stronger attraction to a sea of delocalised electrons