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 is the trend in 1st ionisation energy down a group?


  The outermost electrons are held more weakly as one goes down the group.
• Why are outermost electrons held more weakly down a group?


  They are further from the nucleus in additional shells.
• What effect do inner shell electrons have on outer shell electrons?


  Inner shell electrons shield outer shell electrons from the nucleus's attraction.
• What is the trend in melting points for Group 2 elements?


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


  The metallic bonding weakens as 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 reactivity of Group 2 metals change down the group?


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


  Magnesium reacts slowly in oxygen without a flame.
• What is formed when magnesium reacts with oxygen?

  Magnesium oxide (MgO) is formed.
• What is the balanced equation for the reaction of magnesium with oxygen?

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


  To avoid false results due to different reaction rates of Mg and MgO.
• What is the reaction between magnesium and hydrochloric acid?


  Mg + 2 HCl → MgCl2 + H2
• What is the reaction between magnesium oxide and hydrochloric acid?

  MgO + 2 HCl → MgCl2 + H2O
• How do 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 the reaction of magnesium with steam?


  Magnesium reacts in steam to produce magnesium oxide and hydrogen.
• What is the balanced equation for the reaction of magnesium with steam?

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


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


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

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

  Ba + 2 H2O(l) → Ba(OH)2(aq) + H2(g)
• What observable effects occur when Group 2 metals react with water?


  Fizzing, metal dissolving, solution heating up, and precipitate formation with calcium.
• What is the difference between magnesium's reaction with steam and warm water?


  Magnesium reacts slower with warm water and does not produce a flame.
• What is the balanced equation for magnesium's reaction with warm water?

  Mg + 2 H2O → Mg(OH)2 + H2
• Why is titanium a useful metal?


  It is abundant, has a low density, and is corrosion resistant.
• Why can't titanium be extracted with carbon?


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


  It must be very pure for electrolysis to work.
• How is titanium extracted?


  By reaction with a more reactive metal, such as magnesium.
• What are the steps in extracting titanium?

  1. TiO2 (solid) is converted to TiCl4 (liquid) at 900°C.
  2. TiCl4 is purified by fractional distillation in an argon atmosphere.
  3. Ti is extracted by Mg in an argon atmosphere at 500°C.
• Why is titanium expensive to extract?


  Due to the cost of magnesium, batch processing, argon use, moisture removal, and high temperatures.
• What is the balanced equation for the extraction of titanium using magnesium?


  TiCl4 + 2Mg → Ti + 2MgCl2
• How does calcium oxide remove SO2 from waste gases?


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

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


  Group II sulfates 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?


  By adding acidified barium chloride to the solution.
• What happens when acidified barium chloride is added to a solution containing sulfate ions?


  A white precipitate of barium sulfate forms.
• What is the simplest ionic equation for the formation of barium sulfate?

  Ba2+(aq) + SO4^2-(aq) → BaSO4(s)