3.2.2 Group 2, the alkaline earth metals

• How to test for sulphate ions

  use BaCl and HCI
• Use of CaO or CaO3

  Remove sulfur dioxide
• Use of Mg(OH)2

  Neutralise excess stomach acid , safe as it is weakly alkaline
• Why is Mg(OH)2 only slightly soluble in water?

  Lattice is stronger so fewer free OH- ions are produced and so lower pH, slightly alkaline,
• Why is Mg used and not carbon

  It doesn't react
• What is the use of Mg in extraction of titanium

  It's a reducing agent
• Use of calcium hydroxide

  Agriculture, helps to grow produce, right pH
• Use of magnesium hydroxide

  Neutralise an acid
• Disadvantage of using Barium hydroxide solution

  Produces radioactivity, won't be detected
• Why is Barium hydroxide used to test CO2 instead of limewater

  It's soluble, precipitates forms solution becomes opaque
• Why isn't Barium Sulphate toxic and doesn't harm the patient

  Doesn't dissolve in the bloodstream and not soluble
• Use of Barium sulphate

  Detect stomach ulcers in X-ray scans and it is eaten
• Define the enthalpy change

  Measure of the amount of heat absorbed or evolved when the reaction takes place
• In Group 2 trend in solubility of the sulphates

  It decreases
• In Group 2 trend in solubility of the hydroxides

  Increases down the group
• Metal and steam

  Metal oxide and hydrogen
• Metal and cold water

  Metal hydroxide and hydrogen
• Reaction with Mg and water

  White magnesium gas and hydrogen gas is produced,
• pH change in calcium and water

  Blue and purple
• What is produced when Group 2 metals react with oxygen

  White ionic oxde
• Why Group 2 can be good reducing agents

  They can oxidise themselves, lose electrons easily, become oxidised
• Explain the trend in reactivity the elements of Mg-Ba

  Down the group, it increases, shielding increases, more shells, increase in atomic radius, more electrons, easier for it to be lost due to weaker attraction between nucleus
• Explain the trend in melting point the elements of Mg-Ba

  Down the group it decreases, nuclear charge and atomic radius increases and shielding increases, more electrons, weaken attraction between nucleus and valence electron
• Explain the trend in atomic radius the elements of Mg-Ba

  Atomic radius increases, number of shells increases, shielding increases, weakens attraction between the nucleus and the valence electron,
• Trend in first ionisation energy down the group

  Shielding increases, decreases in IE, less attraction between the valence electron and nucleus, increase nuclear charge
• Trend in reactivity

  Increases, shielding, increase in atomic radius
• Trend in atom size down the group

  Atom size increases
• Which block are they found in

  Block S
• Is there a link between anion charge and solubility?

  Greater solubility of hydroxide and greater the pH indicating its more alkali
• Reason to use calcium hydroxide?

  Alkali which would neutralise and regulate the pH of the soil, not too damaging to soil, crops and wildlife
• Why isn't carbon used?

  Ti reacts with carbon to form a carbide so you get the pure metal
• CaO + H2O + SO2 = CaSO3 + H2O
• What happens when barium meal is digested?

  Prevents X-rays from passing through
• Product in the reaction of Barium Chloride and the sulphate?

  Barium Sulphate
• Why is a precipitate formed?

  It is insoluble
• Why do we need to add a few drops of HCl for the test?

  Remove any carbonate or sulphates which would give similar results
• Describe Group 2 reactions with oxygen

  Burns as a bright white flame, white powder forms, MgO is a solid white,
• How to remove MgO

  Emery paper
• 2MgO + O2

  2MgO
• Mg + H2O

  Mg + H2