Reaction with oxygen

• All of period 3 elements are relatively reactive with oxygen except for Argon
• Sodium reaction with oxygen

  Equation is 2Na(s) + 1/2O2 (g) --> Na2O (s)

  • It burns brightly in oxygen gas with a characteristic yellow flame
  • Forms a white solid
• Magnesium reaction with oxygen

  2Mg(s) + O2(g) --> 2MgO (s)

  • Burns brightly in oxygen gas with a white flame
  • Forms a white solid
• Aluminium reaction with oxygen

  Equation

  4Al (s) +3O2 (g) --> 2Al2O3 (s)

  • Burns with a bright white flame
  • Produces a dull and grey solid
  • Can also react slowly with oxygen in the atmosphere to produce the aluminium oxide that coats the aluminium and stops the rest of aluminium from reacting
• Silicon reacts with oxygen

  Equation

  Si (s) + O2(g) --> SiO2(s)

  • Burns slowly
  • Forms sand
• Phosphorus reacts with oxygen

  Two types of phosphorus

  • Red phosphorus which is a chain of P4 molecules
  • White phosphorus which is a single P4 molecule

  Red phosphorus has to be heated first to react with oxygen while white phosphorus reacts rapidly

  Equations

  • 4P(s) + 5O2 --> P4O10(s)

  When there's little supply of oxygen the following equation happens:

  • 2P(s) + 1.5O2 --> P2O3
• Sulphur reacts with oxygen

  Equations:

  S(s) + O2(g) --> SO2 (g)

  • Burns with a blue flame

  The second reaction occurs in high temperature and a V2O5 catalyst to form sulphur trioxide

  Equation:

  • SO2 (g) + 1/2O2(g) --> SO3(l)
• Properties of the period 3 oxides

  • Oxides of Na, Mg and Al are all ionic bonding and are giant ionic structures with MgO having the highest melting point due to ionic bonds and Al2O3 having more covalent character due to its Al3+ ion being smaller so its more polarising then the Mg2+ and so the electron density is shared between the Al3+ and O2- ions
• Properties of period 3 oxides pt2

  • Silicon dioxide is a giant molecular structure so it has strong covalent bonds and so a high melting point
  • Phosphorus, sulphur oxides are molecular structures so they have Van der Waais forces due to phosphorus oxides being the larger molecule it has the stronger Van der Waais forces then sulphur oxides