GROUP 2

• atomic radius down group 2


  increases:

  - more electron shells therefore bigger atoms
• ionisation energy down group 2


  decreases:

  - atoms get bigger so lower

  - more shielding so lower

  - therefore weaker attraction from nucleus to electron in outer shell

  - less energy needed to remove an electron
• melting point/boiling point down group 2


  decreases:

  - weaker metallic bonding as ions are bigger

  - distance between the positive ions and delocalised electrons increases so electrostatic forces are weaker
• what do group 2 metals form

  2+ ions
• can beryllium react with water


  no
• does magnesium react quicker in steam or water


  steam.
• what is formed when magnesium reacts with steam


  Magnesium oxide and hydrogen
• what does metal and water form


  hydroxide
• general equation for metals and water


  M(s) + 2H2O(l) -> M(OH)2(aq) + H2 (g)
• equation for beryllium and water


  Be (s) + H2O (l) -> X
• equation for magnesium and steam


  Mg (s) + H2O (g) -> MgO (s) + H2 (g)
• equation for calcium and water


  Ca(s) + 2H20(l) -> Ca(OH)2(aq) + H2 (g)
• equation for sr and water


  Sr(s) + 2H2O(l) -> Sr(OH)2(aq) + H2 (g)
• equation for barium and water


  Ba(s) + 2H2O(l) -> Ba(OH)2(aq) + H2 (g)
• reactivity down group 2


  increases:

  - As you go down the group the atoms get bigger and there is more shielding.

  -The 2 outer electrons are further away from the nucleus.

  -Therefore weaker attraction between nucleus and outer electrons.

  -So loses the 2 outer electrons more easily.
• Solubility down group 2 hydroxides


  - increases

  - Mg(OH)2 is least soluble and Ba(OH)2 is most soluble
• Solubility down group 2 sulphates


  -decreases

  - so MgSO4 is most soluble and BaSO4 is least soluble
• what is BaSO4 used for


  It is used in medicine as a 'Barium meal' given to patients who need x-rays of their intestines to make it clearer.
• why do we use BaSO4 even though its toxic

  barium sulphate is insoluble so it is not absorbed into the body.
• how to test for sulphate ions


  - HCl

  - barium chloride (BaCl2)

  
  

  RESULTS: white ppt
• what is BaCl2 used for


  test solutions for sulphate ions
• uses of Mg and equations


  - used to extract Ti from TiO2

  
  

  - TiCl4 + 2Mg -> Ti + 2MgCl2
• What is Mg(OH)2 used for?


  Milk of magnesia - to neutralise excess stomach acid
• What is Ca(OH)2 used for?


  Neutralise acidic soil
• what is CaO used for? and the equation


  - flue gas desulfurisation

  
  

  - CaO + SO2 → CaSO3 +

  
  

  - CaCO3 + SO2 -> CaSO3 + CO2
• observation between steam and magnesium


  - bright white flame

  - white powder
• difference between magnesium + steam and magnesium + water


  magnesium + steam: magnesium oxide and hydrogen. The Mg

  would burn with a bright white flame. The

  MgO appears as a white powder.

  Mg(s) + H2O(g) -> MgO(s) + H2(g)

  
  

  magnesium + water: magnesium hydroxide.

  Mg + 2 H2O -> Mg(OH)2 + H2

  This is a much slower reaction
• how to draw filtration

  
• equation for ionisation energy


  X(g) -> X+(g) + e-
• what is ionisation energy


  The energy required to remove one mole of electrons from one mole of atoms in gas state
• what is electronegativity


  ability of an atom to attract pair electrons towards itself in a covalent bond
• what block are group 2 metals

  s block