Redox 1

• oxidation - loss of electrons, gain of oxygen

  reduction - gain of electrons, loss of oxygen

  Redox reaction - a reaction with both reduction and oxidation

  electronegativity - the tendency of an element to attract a bonding pair of electrons

  oxidation state shows the total number of electrons which have been removed from an element (positive oxidation state) or added to an element (negative oxidation state) to get to its present state

  oxidation involves an increase in the oxidation state

  Reduction involves a decrease in the oxidation state
• Group 1-7 - charge after being made into a stable atom

  Halogens - -1 apart from when bonded to an oxygen (OCl2)

  Hydrogen - -1 apart from when in a metal hydroxide

  Oxygen - -2 apart from when in a peroxide
• redox half equations (acidic)

  1. work out the formulae and balance if required
  2. work out oxidation states of the elements
  3. add electrons to one side of the equation so that the oxidation states balance
  4. balance the number of oxygen with water on the other side
  5. add sufficient H+ ions to one of the sides to balance the charges
• Ionic half-equations (alkaline)

  1. work out the formulae of the species before and after the change. Balance if required
  2. work out the oxidation state of the element before and after the change
  3. add electrons to one side of the equation so that the oxidation state balance
  4. balance the change by adding the number of needed hydroxide ions
  5. add sufficient water molecules to balance the equation
• Combining half-equations

  1. write out two half-equations (one oxidation and one reduction)
  2. multiply one of the equations so the electrons cancel out
  3. add the two equations and cancel out the electrons on either side
  4. if necessary cancel out any other species which appear on both sides.