Group 2

• What happens to atomic radius as one goes down a group in the periodic table?

  Atomic radius increases down the group.
• Why does atomic radius increase down a group?

  Atoms have more shells of electrons, making the atom bigger.
• What happens to the first ionisation energy as one goes down a group?

  The outermost electrons are held more weakly because they are further from the nucleus.
• What causes the outer shell electrons to be more shielded from the nucleus?

  The repulsive force of inner shell electrons shields the outer shell electrons.
• What trend is observed in the melting points of Group 2 elements as one goes down the group?

  Melting points decrease down the group.
• Why do melting points decrease down Group 2?

  The metallic bonding weakens as the atomic size increases.
• What happens to the distance between positive ions and delocalized electrons as atomic size increases?

  The distance increases, weakening the electrostatic attractive forces.
• How does the reactivity of Group 2 metals change down the group?

  Reactivity increases down the group.
• What happens to magnesium when it reacts with oxygen?

  Magnesium will react slowly in oxygen without a flame.
• What is the chemical equation for the reaction of magnesium with oxygen?

  2 Mg + O2 → 2 MgO
• Why must magnesium oxide be removed before doing reactions with magnesium ribbon?

  Because both Mg and MgO would react but at different rates, giving a false result.
• What are the products of the reaction between magnesium and hydrochloric acid?

  MgCl2 and H2.
• What is the reaction of magnesium oxide with hydrochloric acid?

  MgO + 2 HCl → MgCl2 + H2O
• What happens when Group 2 metals react with oxygen?

  They burn in oxygen, producing metal oxides.
• What is the appearance of magnesium oxide when formed?

  It appears as a white powder.
• What is produced when magnesium reacts with steam?

  Magnesium oxide and hydrogen gas.
• What is the equation for the reaction of magnesium with steam?

  Mg(s) + H2O(g) → MgO(s) + H2(g)
• How do the other Group 2 metals react with cold water?

  They react with increasing vigour down the group to form hydroxides.
• What is the general reaction of calcium with water?

  Ca + 2 H2O(l) → Ca(OH)2(aq) + H2(g)
• What is the general reaction of strontium with water?

  Sr + 2 H2O(l) → Sr(OH)2(aq) + H2(g)
• What is the general reaction of barium with water?

  Ba + 2 H2O(l) → Ba(OH)2(aq) + H2(g)
• What observable signs indicate a reaction of Group 2 metals with water?

  Fizzing, the metal dissolving, and the solution heating up.
• What happens with calcium when it reacts with water?

  A white precipitate appears, which is less with other metals down the group.
• What is the reaction of magnesium with warm water?

  Mg + 2 H2O → Mg(OH)2 + H2
• How does the reaction of magnesium with steam differ from that with warm water?

  The reaction with steam is much faster and produces a flame, while the reaction with warm water is slower and does not produce a flame.
• What is titanium used for?


  It is used for making strong, light alloys for use in aircraft.
• Why can't titanium be extracted with carbon?

  Because titanium carbide (TiC) is formed rather than titanium.
• Why can't titanium be extracted by electrolysis?

  Because it has to be very pure.
• What is the first step in extracting titanium?

  TiO2 (solid) is converted to TiCl4 (liquid) at 900°C.
• What is the second step in extracting titanium?

  The TiCl4 is purified by fractional distillation in an argon atmosphere.
• What is the third step in extracting titanium?

  The Ti is extracted by Mg in an argon atmosphere at 500°C.
• Why is titanium expensive to extract?

  Due to the expensive cost of magnesium and the batch process involved.
• What are the reasons for the high cost of titanium extraction?

  • Expensive cost of magnesium
  • Batch process is slower and requires more labor
  • Energy loss when cooling reactors
  • High temperatures required in both steps
• What is the reaction for extracting titanium using magnesium?

  TiCl4 + 2Mg → Ti + 2MgCl2
• How does calcium oxide help in flue gas desulfurization?

  It reacts with sulfur dioxide in a neutralization reaction.
• What is the equation for the reaction of sulfur dioxide with calcium oxide?

  SO2 + CaO → CaSO3
• What happens to Group II sulfates down the group?

  They become less soluble down the group.
• Which Group II sulfate is the least soluble?

  BaSO4 is the least soluble.
• How can sulfate ions be tested for in a solution?

  By adding acidified barium chloride, which forms a white precipitate of barium sulfate.
• What is the simplest ionic equation for the reaction of barium ions with sulfate ions?

  Ba2+(aq) + SO4^2-(aq) → BaSO4(s)