Group 2

• what happens to atomic radius down group 2?

  increases
• what happens to melting point down group 2?

  all generally high - no clear trend
• what happens to ionisation energy down group 2?

  decreases
• what is calcium oxide used for?

  to treat acidic soils
• what is reacted with titanium oxide to form Ti4 and CO?

  chlorine and carbon
• what is Titanium chloride then reduced by to form titanium?

  magnesium
• state and explain the trends in melting points down group 2

  1. down the group the size of the cation increases
  2. so the distance between the cations and delocalised electrons increases
  3. so strength of metallic bonding decreases and therefore melting point decreases
• explain why calcium has a higher melting point than strontium

  1. ca2+ ions are smaller that sr+ ions so the distance between the ca2+ ions and delocalised electrons is smaller
  2. so metallic bonding in Ca is stronger so more energy is required to melt Ca
• what is used as a simple test for sulphate ions?

  acidified barium chloride
• what is Mg(OH)2 used to treat?

  Indigestion / neutralises stomach acid
• group 2 hydroxides increase in solubility down the group - become more soluble
• describe the reaction of magnesium with water

  React slowly with cold water but rapidly with steam
• describe the solubility of magnesium hydroxide

  sparingly soluble
• calcium reacts mildly with cold water to form a white precipitate
• describe the solubility of calcium hydroxide

  sparingly soluble - used as lime water slaked lime used to treat acidic soil to provide optimal conditions for plants to grow
• strontium is less reactive than calcium so it does not react with cold water
• barium reacts vigorously with cold water forming barium hydroxide which is very soluble
• barium is more reactive than calcium so it reacts vigorously with cold water forming barium hydroxide which is insoluble
• the reaction between sodium carbonate and dilute sulfuric acid produces carbon dioxide gas, sodium sulfate and water.
• strontium reacts vigourously with water and is more soluble than calcium and magnesium
• barium reacts vigourously with cold water and is the most souble in group 2 - produces an alkaline solution
• group 2 sulfates decrease in solubility down the group
• barium hydroxide is the most soluble and barium sulfate is the least soluble in group 2
• magnesium oxide is used as a mild antacid
• barium sulfate is used as a contrast medium in x-rays
• why is barium sulfate safe to eat to outline xrays - barium meal?

  insoluble and non - toxic
• barium sulfate is used to test for sulfate ions as it is so insoluble, when barium chloride is reacted with a sulfate it produces an insoluble barium sulfate precipitate
• explain why acid should be added before BaCl2 when testing for sulfate ions

  1. carbonate ions in solution will react with BaCl2 to form BaCO3
  2. BaCO3 will give a false negative for sulfate ions
  3. so HCl is added to remove CO3
• state why H2SO4 should not be used to acidify BaCl2

  sulfuric acid contains the sulfate ion which will react with BaCl2

  form BaSO4 every time a sulfate ion comes from the acid not the solution
• suggest why MgCl2 wouldnt be a suitable test for sulfate ions

  MgCl2 would react with sulfate ion to form MgSO4

  however group 2 sulfate solubility decreases down the group

  so MgSO4 is soluble and wouldnt produce a visible precipitate