Transition Metals

• What is a transition metal?

  A metal that can form one or more stable ions with a partially filled d sub-level
• Why is scandium not a transition metal?


  When it forms a 3+ ion, it has an empty d sub-level
• Why is zinc not a transition metal?

  Has a full d sub-level, even when it forms Zn2+
• What are 2 physical properties of transition metals?

  High density, high melting and boiling point
• What are 4 chemical properties of transition metals?

  Form complex ions, form coloured compounds, good catalysts, variable oxidation states
• What is a complex ion?

  Metal ions surrounding ligands
• What is a ligand?


  An atom, ion or molecule that donates a pair of electrons to a central metal ion = coordinate bond
• What is the coordination number?

  Number of coordinate bonds that are formed with the central metal ion
• Which molecules tend to have a coordination number of 6?

  Small ligands (H20/NH3)
• Which molecules tend to have a coordination number of 4?

  Larger ligands (Cl-)
• How do you work out the oxidation state of a metal ion?

  total charge - sum of charge on ligands
• Colour of Ti2+


  +2, violet
• Colour of Ti3+


  +3, purple
• Colour of V2+


  +2, violet
• Colour of V3+


  +3, green
• Colour of VO 2+


  +4, blue
• Colour of VO2 +

  +5, yellow
• Colour of Cr3+


  +3, green
• Colour of Cr2O7 2-


  +6, orange
• Colour of Mn2+


  +2, pale pink
• Colour of MnO4 2-


  +6, green
• Colour of MnO4-


  +7, purple
• Colour of Fe2+


  +2, pale green
• Colour of Fe3+


  +3, yellow
• Colour of Co2+


  +2, pink
• Colour of Ni2+


  +2, green
• Colour of Cu2+


  +2, pale blue
• How do optical isomers form?

  An ion can exist as two non superimposible mirror images
• What is cisplatin?


  Complex of platinum with two chloride ions and two ammonia molecules in a square planar shape
• What is cisplatin used for?

  Treat cancer by preventing cancer cells from reproducing
• Why do 3d orbitals split into different energy levels?

  Ligands bond to the ions, some orbitals are given more energy than others
• What energy do electrons absorb to be excited

  Absorb energy equal to the energy gap, from visible light
• What does energy gap depend on?

  Oxidation state of central metal ion, ligands and coordination number
• Why are transition metals coloured?

  Some frequencies are reflected, and they combine to make a complement of the colour
• What does spectroscopy do?

  Used to determine the concentration of a solution by measuring how much light it absorbs. More coloured, more light it absorbs
• Why is spectroscopy used?

  Easy to get multiple readings, quick, can measure low concentrations
• What does haemoglobin contain?

  Four of lone pairs come from nitrogen atoms, globin and either an oxygen or water molecule
• What occurs in the lungs?

  Water ligands substituted for oxygen molecules to form oxyhaemoglobin
• What is carboxyhaemoglobin?


  Haemoglobin substitutes water ligands for carbon monoxide ligands, starving organs
• Which complexes are hard to reverse?

  Multidentate ligands are more stable than monodentate ligands, so ligand bonds are stronger