G2

• G2 - the atomic radius increases as you go down the group , more electron shells
• G2 - ionisation energy decreases as you go down the group. More shells means more shielding means weaker attraction between nucleus and outer electron
• G2 - generally melting point decreases

  Ions will get bigger as you go down, greater distance between positive nuclei and delocalized electrons. Makes it easier to break bonds

  NOTE: G2 metals have metallic bonds
• G2 react with water to form bases
• G2 can react with water to form metal hydroxides just like group 1 but remember it will form 2 OH per mole of metal eg. Sr(OH)2
• G2 - reactivity increases with water
• Reactivity for G2 increase because atom gets larger. Electron is further away from nucleus making it easier to remove, which means it is more reactive
• If an anion has a double negative charge they become less soluble as you go down the group
• G2 hydroxides and sulfates have opposite solubility in water
• You can test for sulfates using barium chloride
• to test for sulfates first add HCL - to remove any carbonates in solution then add barium chloride
• if sulfate is present you will observe a white precipitate
• Group 2 compounds can be used to neutralise acids
• You can use Ca(OH)2 / slaked lime / to neutralise acidic soil
• Mg(OH)2 is used as antacids and used to neutralise excess stomach acid
• Ba2+ (aq) + S04 2- (aq) --> BaSO4 (s)
• Barium sulfate is also known as barium meal
• Barium sulfate can be used to identify problems in the digestive tract
• Barium sulfate absorbs x-rays
• Barium compounds ARE toxic but barium sulfate is insoluble so will not get absorbed into blood
• Mg is used to extract titanium from it's ore
• TiO2 is converted to TiCl4 by heating with carbon and chlorine gas
• TiCl4 is passed through fractional distillation to purify it and is then reduced using magnesium
• TiCl4 + 2Mg --> Ti + 2MgCl2
• Titanium is light weight but strong, commonly used in planes
• Calcium carbonate and oxide can be used to remove sulfur dioxide emissions
• 'wet scrubbing' - alkali used to neutralise sulfur dioxide in flue gases
• Wet scrubbing involves spraying acidic sulfur dioxide gas with calcium carbonate or oxide
• CaCO3 (S) + 2H20 + SO2 (g) --> CaSO3(s) + 2H2O + CO2 (g)

  CaSO3 (s) - calcium sulfite
• for flame tests in blue flame:

  Calcium is dark red

  strontium is red

  Barium is green
• test ammonium compounds and hydroxides with litmus paper
• test for ammounium compounds

  • Add sodium hydroxide
  • if ammonia is present gas will be released
  • use litmus paper to see colour change from red to blue

  NH4+ + OH- --> NH3 + H2O
• hydroxides are alkaine and will turn red litmus paper blue but further tests are needed
• Testing for carbonates

  CO2 gas will turn limewater cloudy (after adding HCL)
• test for carbonates, if no change test for sulfates if no change then test for halides