3.1.1 oxidation reduction and redox equations

• oxidation is the loss of electrons
• reduction is the gain of electrons
• definition of oxidation in terms of oxygen

  gain of oxygen
• definition of reduction in terms of oxygen

  loss of oxygen
• definition of oxidation in terms of hydrogen

  loss of hydrogen
• definition of reduction in terms of hydrogen

  gain of hydrogen
• definition of oxidation in terms of electrons

  loss of electrons
• definition of reduction in terms of electrons

  gain of electrons
• definition of oxidation in terms of oxidation state/number

  oxidation number increases
• definition of reduction in terms of oxidation state/number

  oxidation number decreases
• the oxidation number of an atom is the charge that would exist on an individual atom if the bonding were completely ionic
• for elements in their standard states, the oxidation number for each atom is 0
• for simple ions (an individual atom with a charge) the oxidation number is the same as the charge
• group 1 atom oxidation state: +1

  group 2 atom oxidation state: +2

  Al: +3

  Fluorine: -1

  Hydrogen: +1 (has exceptions)

  Oxygen: -2 (has exceptions)

  Other halogens (Cl, Br, I): -1 (has exception)
• if an atom is oxidised the oxidation number becomes more positive
• if an atom is reduced the oxidation number becomes more negative
• what acronym is used to write half equations

  Every One Hates Chem
• what does every one hates chem stand for when writing balanced half equations

  • Every: balance element which is reduced or oxidised
  • One: balance Oxygen atoms by adding water
  • Hates: balance H atoms by adding H+
  • Chem: add necessary number of electrons to balance the Charge on both sides (electrons added to most positive side)
• exam hint: if you’re told a solution is acidified the examiner is telling u that H+ is needed to balance your redox half equations
• oxidising agent is an electron acceptor
• an oxidising agent brings about oxidation and itself is reduced
• reducing agent is an electron donor
• a reducing agent brings about reduction and itself is oxidised
• disproportionation is when an element is simultaneously reduced and oxidised