Periodicity

• Reaction of sodium with water- observation

  Floats, fizzes and moves on the surface of the water, molten. melts into a ball and disappears
• pH of sodium with water

  alkali, 12-14
• Sodium oxide formula

  Na2O
• What is the structure bonding in NaO

  ionic lattice, ionic bonding between Na+ ions an O2- ions
• Why is the melting point of sodium oxide high?

  ionic lattice with strong electrostatic forces of attraction between ions (Na and O) so a lot of energy is required to break it
• formation of sodium oxide- observation, burning Na in air

  burns vigorously in air with yellow flame and white solid formed
• Describe sodium as an alkali metal.

  needs to be stored in oil to prevent it from reacting with air. can be cut with a knife, exposing a shiny surface which tarnishes quickly - forming layer of Na2O.
• sodium oxide and water equation

  Na2O+H2O--> 2NaOH
• sodium oxide and HCL equation

  Na2O+2HCL--> 2NaCl+H2O
• sodium oxide and sulfuric acid equation

  Na2O+H2SO4--> Na2SO4+H2O
• sodium oxide and water reaction description

  sodium oxide dissolves in water and the oxide ion acts as a base and accepts H+ from the water or acid
• how quickly does magnesium react with water?

  magnesium reacts very slowly with water forming a solution of pH 9-10. But vigorously with water vapour above 100c (steam)... in absence of air.
• magnesium and water equation

  Mg+2H2O(l)--> Mg(OH)2+H2
• magnesium and water vapour equation

  Mg+H2O(g)--> MgO+H2
• What is the structure bonding in magnesium oxide?

  ionic lattice structure, ionic bonds between positive Mg ions and negative O ions.
• why is the melting point of magnesium oxide high?

  due to the strong electrostatic forces of attraction between oppositely charged ions (Mg and O) in the ionic lattice, which require a large amount of energy to break
• why is the melting point of magnesium oxide high than sodium oxide

  Mg2+ ions is smaller and has a higher 2+ charge than the Na+ ion. the electrostatic forces of attraction between the Mg2+ ions and the O2- ions are higher than between the Na+ and O2- ions
• magnesium burning in oxygen observation

  vigorously, bright white light and a white solid forms
• magnesium oxide and water equation

  MgO+H2O--> Mg(OH)2
• magnesium and oxygen equation (burning)

  2Mg+O2--> 2MgO
• pH of solution of magnesium oxide

  slightly alkali, around pH9-10
• magnesium oxide and HCL equation

  MgO+2HCL--> MgCl2+H2O
• magnesium oxide and H2SO4

  MgO(s) + H2SO4(aq) --> MgSO4(aq) + H2O(l)
• Al reaction with oxygen

  2Al + 3/2O2 --> Al2O3
• Burning Al observations

  Slow, n/a flame colour, produces Al2O3
• Describe reaction of Al2O3 in water

  Partially ionic an partially covalently bonded, insoluble in water.
• Why is Al2O3 amphoteric? use equations

  Act as an acid or base, forming salts when reacting with an acid or base.

  
  

  Al2O3(s) + 3H2SO4(aq) --> Al2(SO4)3(aq) + 3H2O

  
  

  Al2O3(s) + 2NaOH(aq) + 3H2O --> 2NaAl(OH)4(aq)
• Reaction of Si with oxygen

  Si + O2 --> SiO2
• Reaction of Si in air/burning? observations

  Slow, n/a colour, produces SiO2
• The Reaction of SiO2 with Water

  Giant covalent structure means insoluble in water.
• Reaction of SiO2 with acid/base.

  React with bases to form salts so classified as acidic.

  
  

  SiO2(s) + 2NaOH(aq) --> Na2SiO3(aq) + H2O(l)
• Reaction of P with oxygen

  P4(s) + 5O2 --> P4O10(s)
• Burning P in air observations

  Spontaneously combusts, brilliant white flame, produces P4O10
• Reaction of phosphorous oxide with water.

  Simple covalent oxide forms acidic solutions.

  
  

  P4O10(s) + 6H2O --> 4H3PO4(aq)

  
  

  Phosphoric(V) acid produces.

  
  

  H3PO4 --> 3H+(aq) + PO4(3-)(aq), dissociate to conjugate base

  
  

  Strong acid, pH = 1
• Phosphorous oxide acting as acid or base?

  Acidic so neutralise bases.

  
  

  P4O10(s) + 12NaOH --> 4Na3PO4(aq) + 6H2O(l)
• Reaction of S with oxygen

  S(s) + O2 --> SO2

  
  

  Can form SO3
• Burning S in air observations

  Burns steadily, blue colour flame, produces SO2
• Reactions of SO2 in water

  SO2 + H2O --> H2SO3(aq)

  
  

  Sulfurous acid (sulfuric(IV) acid).

  
  

  Simple covalent oxides form acidic solution of pH = 1. Dissociates:

  
  

  H2SO3 -- 2H+ + SO3(2-)
• Reactions of SO3 in water

  SO3 + H2O --> H2SO4(aq)

  
  

  Sulphuric(VI) acid. Simple covalent oxide forms strongly acidic solution of pH = 1. Dissociates:

  
  

  H2SO4 --> 2H+ + SO4(2-)
• Sulfur dioxide acting as a base or acid.

  Acidic, neutralises bases.

  
  

  SO2(g) + 2NaOH(aq) --> Na2SO3(aq) + H2O