Group 2 and 7

• What happens to the reactivity going down group 2

  Increases
• Why does reactivity increase going down group 2


  Successively easier to remove electrons to form the 2+ ion
• Why does the effective charge remain approximately constant

  The next element has more protons but more she losing so the cancel out
• Why is the 2nd ionisation energy higher than the 1st

  the electron is being removed from an already positive ion
• what do group 2 oxides produce when reacted with water?

  • alkaline solution
  • hydroxide
• Will mg react quickly slowly with O2 without a flame?

  Slowly
• Which group 2 oxide is atmopheric

  BeO
• Atomopheric

  Can act as both acid and base
• Why is there an increase in radius?

  Higher principle energy levels being filled whose orbitals Are located further from the nucleus
• How can no reaction of group 2 oxide + acid be prevented?

  • use oxide in powder form
  • stir mixture
• What is calcium hydroxide also known as?

  Limewater
• Which element does not react with water?

  Beryllium
• Observations when hydroxide is produced

  • Fizzing
  • metal dissolve
  • solution heating up
  • (with calcium) white precipitate formed
• Group 2 reaction hydroxide with dilute acids

  Colourless solution of metal salts
• Hydroxide + dilute hydrochloric acid

  Metal chloride + water
• Metal hydroxide + dilute sulphuric acid

  • Metal sulfate
  • water
• Why might a reaction not occur with a group 2 oxide + acid?

  • insoluble surfaces form at the surface of the oxides
  • solid beneath can’t react with the acid
• CaO + H2O -> Ca(OH)2

  PH + observation

  • ph12
  • vigorous
  • water boils off
  • CaO solid expands and crack open
• MgO + H2O -> Mg(OH)2

  PH and observation

  • PH9
  • slightly soluble
• Magnesium reaction with steam

  • vigorous reaction

  Mg + H2O -> MgO + H2
• Magnesium reaction with cold water

  • react extremely slowly
  • Slightly alkaline (9 to 10)

  Mg + 2H2O -> Mg(OH)2 + H2
• Reaction of group 2 metal and oxygen

  2M + O2 -> 2MO
• Group 2 metal + water

  • metal hydroxide
  • hydrogen

  M + 2H2O -> M(OH)2 + H2
• Reaction of group 2 element with oxygen

  • Will burn

  2Mg + O2 -> 2MgO
• group 2 metal reactions with cold water

  • Increase in vigour going down the group
  • form hydroxides
• Group 2 reaction with chlorine

  • Metal chloride

  Mg + Cl2 -> MgCl2
• Group 2 metal oxide + dilute sulfuric acid

  Metal surface + water
• Group 2 oxide + dilute hydrochloric acid

  Metal chloride + water
• What happens to the solubility of the hydroxide going down?

  • solubility increases
  • become more soluble
• What happens to the pH of the hydroxide going down the group?

  • PH increases
  • Become more alkaline
• Why do hydroxides become more alkaline going down the group?

  There is a higher concentration of OH-ions formed
• What is the appearance of group 2 hydroxide when not soluble?

  White precipitate
• Is magnesium hydroxide soluble or insoluble in water?

  Insoluble
• Magnesium hydroxide + water ionic equation

  Mg2+ + 2OH- -> Mg(OH)2
• What is magnesium hydroxide used for in medicine?

  • Milk of magnesia
  • Neutralise excess acid in the stomach
• is calcium hydroxide soluble in water?

  Reasonably soluble
• What is calcium hydroxide used for?

  Used in agriculture to neutralise acidic soil
• What happens to the solubility of the sulphates going down the group?

  Solubility decreases
• what happens when barium metal is reacted with sulphuric acid?

  • Slow reaction
  • Insoluble barium sulphate produced which will cover the surface of the metal
• Definition of thermal decomposition

  The breakdown of a compound into two or more different substances using heat