transition metals

• what are transition metals?

  have a partially filled 3d subshell
• properties of transition metals?

  • form complexes
  • coloured
  • variable oxidation states
  • catalysts
• what is a complex?

  when ligands form coordinate bonds (dative) to metal ion.
• what is a ligand?


  species which donates 1 or more lone pair electrons to metal ion
• complex ions consist of...

  • metal ion
  • ligand

  e.g [Cu(H2O)6]2+
• how are ligands classified?

  the number of coordinate bonds
• 3 types of ligands?

  • monodentate
  • bidentate
  • multidentate
• monodenate ligands


  • form 1 coordinate bond to metal ion
  • e.g H20 , Cl- , NH3 , CN-
• what is the overall charge of complex ion?

  charge on ligand + metal ion oxidation state

  e.g. [CuCl4]2-

  -2 charge for complex (overall)

  x4 Cl- charge = -4

  Cu charge must be +2
• Bidentate ligand


  • form 2 coordinate bonds. donates 2 lone pairs to metal ion
  • e.g NH2CH2CH2NH2 (ethan-1,2-diamine) and C2O4 2- (ethandioate)
• multidentate ligand


  • form 3 or more coordinate bonds.
  • e.g EDTA and porphine
• what type of isomerism is shown in each ligand?

  bidentate = optical

  monodetate = cis-trans
• shapes of complex ions?

  • octahedral = 6 coordinate bonds
  • tetrahedral = 4 coordinate bonds
  • square planar = 4 coordinate bonds
  • linear = 2 coordinate bonds
• example of octahedral shape?

  NH2CH2CH2NH2 (EN)+ Cu (II)
• example of tetrahedral shape?

  [CuCl4]2-
• example of square planar? use?

  cisplatin - cancer treatmeant

  [Pt(NH3)2CL2]
• example of linear shape?

  [Ag(NH3)2]+
• how are coloured ions formed?

  • partial d subshell means electrons move between orbitals
  • can be promoted to higher levels
  • need energy from absorbing light at certain frequencies to be promoted
• factors affecting colour of ion?

  • type of ligand
  • coordination number
  • shape of complex
  • oxidation state
• calorimetry process:


  • make solutions of known concentrations
  • measure absorbance values
  • plot concentration on x axis
  • plot absorbance on y axis
  • use graph to work out unknown concentration
• what happens in a ligand substitution reaction?

  metal-ligand bonds are broken and replaced.
• effect of coordination no when small ligands are replaced by small ligands?

  • no change in coordination
  • e.g. [Co(H2O)6]2+ + 6NH3 -> [Co(NH3)6]2+ + 6H20
• effect of chlorine in ligand substitution involving ammonia or water?

  • chlorine is larger
  • change in coordination number
  • e.g [Cu(H2O)]2+ + 4CL- -> [CuCl4]2- + 6H2O