Transition metals

• What is the general property of transition metals?

  They have an incomplete d sub-level.
• Which elements are considered transition metals?

  Elements from Sc to Cu.
• What is the electron configuration of Sc?

  1s22s22p63s23p6 4s23d1
• What is the electron configuration of Cu?

  1s22s22p63s23p6 4s13d10
• What is the electron configuration of Zn?

  1s22s22p63s23p6 4s23d10
• Why does zinc not qualify as a transition metal?

  Zinc forms only a +2 ion with a complete d orbital.
• What are the characteristics of transition metals?

  • Complex formation
  • Formation of coloured ions
  • Variable oxidation states
  • Catalytic activity
• What is a complex in chemistry?

  A central metal ion surrounded by ligands.
• What is a ligand?

  An atom, ion, or molecule donating a lone pair.
• What is co-ordinate bonding?

  Bonding where shared electrons come from one atom.
• What is the co-ordination number?

  The number of co-ordinate bonds to a metal ion.
• What happens during ligand substitution reactions?

  Ligands are exchanged without changing coordination number.
• What is the result of adding concentrated chloride ions to aqueous ions?

  It leads to a ligand substitution reaction.
• What is the effect of chloride ions on coordination number?

  Chloride ions can change coordination number from 6 to 4.
• What is the shape of [CuCl4]2- complex?

  Tetrahedral in shape.
• What is the shape of [CoCl4]2- complex?

  Tetrahedral in shape.
• What happens when solid copper chloride is dissolved in water?

  It forms the aqueous [Cu(H2O)6]2+ complex.
• What is haem in terms of ligands?

  An iron(II) complex with a multidentate ligand.
• What is the chelate effect?

  Stability increases when monodentate ligands are replaced.
• How does the chelate effect relate to entropy?

  It increases entropy due to more product moles.
• What is the significance of EDTA complexes?

  They can remove toxic heavy metal ions.
• How do you calculate the concentration of copper(II) ions in river water?

  Use moles of EDTA to find Cu2+ concentration.
• What is the concentration of copper(II) ions if 6.45 cm3 of 0.0150 mol dm–3 EDTA is used?

  0.00387 mol dm–3.
• What shapes do transition metal ions commonly form?

  Octahedral, tetrahedral, and square planar complexes.
• What is isomerism in complex ions?

  Complexes can show cis-trans and optical isomerism.
• What causes colour changes in transition metal complexes?

  Changes in oxidation state, coordination number, or ligand.
• How does colour arise in transition metal complexes?

  From electronic transitions between d orbitals.
• What happens when a ligand is changed in a complex?

  It alters the energy split between d orbitals.
• What is the equation relating energy difference and frequency of light absorbed?

  ΔE = hv.
• What is Planck's constant?

  6.63 × 10–34 J s.
• What is the speed of light?

  3.00 x 10^8 m s–1.
• Why do some compounds lack colour?

  They have no d electrons to transfer energy.
• What happens to the colour of [Co(H2O)6]2+ when it reacts with NH3?


  It changes from pink to yellow/brown.
• What is the effect of changing both ligand and coordination number?

  It alters the properties and colour of the complex.
• How does the absorption of light relate to the colour of a solution?

  A solution appears blue if it absorbs orange light.
• What is the relationship between wavelength and energy difference?

  ΔE = hc/λ.
• What is the unit for frequency of light absorbed?

  Hz or s–1.
• What is the significance of the 1:1 ratio in EDTA titrations?

  It indicates a consistent reaction with metal ions.
• What happens to the entropy during the formation of EDTA complexes?

  Entropy increases due to more product moles.
• What is the effect of the chelate effect on complex stability?

  It increases stability by replacing monodentate ligands.