1.1

• Oxidation number


  The number of electrons added or taken away from an element to make it neutral
• Determining oxidation number


  1. In ion, sum of oxidation numbers = the charge of the ion

  2. In compound, sum of oxidation numbers = 0
• Oxidation number of elements

  • Uncombined element = 0
  • In simple ion, oxidation state = charge of the ion (e.g. Fe = 3+, O = 2-)
  • Oxidation of Oxygen = -2, except in peroxides (H2O2) where it = -1
  • Oxidation number of Hydrogen = +1, except in metal hydrides (e.g. NaH) where it = -1
• Oxidation number of group elements

  • Group 1 = +1
  • Group 2 = +2
  • Group 3 = +3
  • Group 4 = +4 OR -4
  • Group 5 = -3
  • Group 6 = -2
  • Group 7 = -1
• Total of all oxidation states must equal the overall charge of the species
• In molecules and more complex ions, the more electronegative element is assumed to be the negative ion
• Range of oxidation states for transition metals

  • Ti max +4
  • V max +5
  • Cr max +6
  • Mn max +7
  • Fe highest seen +6
• Atom


  The smallest part of an element that can exist, consisting of a nucleus containing protons and neutrons surrounded by energy levels that electrons occupy
• Ion


  An atom or group of atoms with an electrical charge, gained or lost by the addition or removal of electron(s)
• Molecule


  Two or more atoms/groups of atoms that are chemically bonded
• Compound


  Material formed by the chemical bonding of two or more elements
• Element


  A substance with only one type of atom, with its own symbol on the periodic table
• Formula


  Tells you the number and types of elements present in one mole of a compound
• Ionic equations


  Remove spectator ions, include state symbols
• Types of reactions with ionic equations

  • Neutralisation
  • Precipitation
  • Displacement
• Ions

  • Ammonium (NH4^+)
  • Hydrogen carbonate (HCO3^-)
  • Hydroxide (OH^-)
  • Carbonate (CO3^2-)
  • Nitrate (NO3^-)
  • Oxide (O^2-)
  • Sulfide (S^2-)
  • Phosphate (PO4^3-)
  • Sulfate (SO4^2-)