Group 2

• Atomic radius of group 2

  The atomic radius of group II metals increases down the group - additional electron

  shells.
• Reactivity of group 2

  Reactivity increases down the group - Increased electron shielding down the group makes the outer electrons easier to lose.
• Ionisation Energy of group 2

  The first ionisation energy of group 2 metals decreases down the group due to a greater atomic radius and increased amounts of shielding.
• Melting point of group 2

  The group 2. elements are metallic meaning the larger the ions within the metallic structure, the

  weaker the attractive forces as the attractive force has to act over a much greater distance.

  Therefore the melting points decrease down the group
• Reactions with Water of group 2.

  React with water in a redox reaction to produce a metal hydroxide and hydrogen.

  The metal hydroxide form as an alkaline solution: group II alkali metals.

  E.G:

  
• Magnesiums reaction with water and steam.

  Mg reacts very slowly with water. Is much faster with steam as it provides reaction with extra energy.

  When steam is used, the magnesium burns with a bright white flame to form hydrogen and magnesium oxide, a white powder.

  
• Solubility of Hydroxides

  Solubility INCREASES down the group. Mg(OH)2 - Magnesium is the LEAST soluble. Ba(OH)2 is the MOST soluble.

  All G2 hydroxides appear as white precipitates when insoluble.

  Mg(OH)2 can therefore be used in medicine as an antacid and neutralise excess stomach acid..

  Can neutralise acidic soils
• How does the solubility of sulfates change down the group?

  It decreases down the group
• Which sulfate is the most soluble?

  Mg(SO)4
• Which sulfate is the least soluble?

  Ba(SO)4
• What is the medical use of Ba(SO)4?

  It is used as a 'Barium meal' for x-rays
• Why is Ba(SO)4 safe to use in medicine despite barium's toxicity?

  Its low solubility prevents absorption into blood
• What does barium absorb during x-ray imaging?

  X-rays
• What is barium chloride used for?

  It tests for sulfate ions
• What happens when barium chloride reacts with sulfate ions?

  It forms barium sulfate as a white precipitate
• What are the key points about the solubility of sulfates?

  • Solubility decreases down the group
  • Mg(SO)4 is the most soluble
  • Ba(SO)4 is the least soluble
• What are the uses and properties of Ba(SO)4 in medicine?

  • Used as a 'Barium meal' for x-rays
  • Absorbs x-rays for imaging
  • Low solubility prevents blood absorption
• What is the reaction of barium chloride with sulfate ions?

  • Barium chloride reacts with sulfate ions
  • Forms barium sulfate
  • Produces a white precipitate
• Metal extraction.

  Magnesium is used in the extraction of titanium from titanium chloride via a displacement as Mg is more reactive

  reaction

  Titanium is a very useful metal because it is abundant,

  has a low density and is corrosion resistant.

  Example:

  
• Steps in extracting titanium using magnesium

  . TiO2 (solid) is converted to TiCl4 (liquid) at 900C:

  2. The TiCl4 is purified by fractional distillation in an argon

  atmosphere.

  3. The Ti is extracted by Mg in an argon atmosphere at 500

  Titanium cannot be extracted with carbon

  because titanium carbide (TiC) it is formed

  rather than titanium.

  Titanium cannot be extracted by electrolysis

  because it has to be very pure
• Why is titanium expensive.

  The expensive cost of the magnesium

  2. This is a batch process which makes it expensive because the process is slower (having to fill up and empty reactors takes time) and requires more labour and the energy is lost when the reactor is cooled down after stopping

  3. The process is also expensive due to the argon, and the need to remove moisture (because TiCl4 is susceptible to hydrolysis).

  4. High temperatures required in both steps
• Flue Gas Removal

  Calcium oxide reacts with sulfur dioxide to remove it from factory pollutants and prevent it from being released into the atmosphere.

  This forms calcium sulfite and water.

  Example