Transition Metals

• What is the general property of transition metals related to their electron configuration?

  Transition metals have an incomplete d sub-level in atoms or ions.
• What is the electron configuration of Scandium (Sc)?

  1s²2s²2p⁶3s²3p⁶4s²3d¹
• What is the electron configuration of Copper (Cu)?

  1s²2s²2p⁶3s²3p⁶4s¹3d¹⁰
• What is the electron configuration of Zinc (Zn)?

  1s²2s²2p⁶3s²3p⁶4s²3d¹⁰
• Why is zinc not considered a transition metal?

  Zinc can only form a +2 ion with a complete d orbital, not an incomplete 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 complex is a central metal ion surrounded by ligands.
• What is a ligand?


  A ligand is an atom, ion, or molecule that can donate a lone electron pair.
• What is co-ordinate bonding?


  Co-ordinate bonding is when the shared pair of electrons in a covalent bond comes from only one of the bonding atoms.
• What is the co-ordination number?


  The co-ordination number is the number of co-ordinate bonds formed to a central metal ion.
• What are the types of ligands based on their bonding capabilities?

  • Monodentate: Form one coordinate bond (e.g., H2O, NH3, Cl-)
  • Bidentate: Form two coordinate bonds (e.g., NH2CH2CH2NH2, C2O4^2-)
  • Multidentate: Form multiple coordinate bonds (e.g., EDTA^4-)
• What happens during substitution reactions involving ligands?

  Ligands can be exchanged without changing the co-ordination number in some cases.
• What is the result of the substitution reaction between [Co(H2O)6]²⁺ and NH3?

  [Co(NH3)6]²⁺ and 6H2O are produced.
• What occurs when a high concentration of chloride ions is added to an aqueous ion?

  It leads to a ligand substitution reaction and can change the co-ordination number.
• What is the shape of the complex [CuCl₄]^2-?

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

  It forms the aqueous [Cu(H2O)₆]²⁺ complex, not the chloride [CuCl₄]^2- complex.
• What is haem in relation to transition metals?

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


  The chelate effect is the increased stability of a complex when a monodentate ligand is replaced by a bidentate or multidentate ligand.
• How does the substitution of ligands affect the stability of complexes?

  Substituting monodentate ligands with bidentate or multidentate ligands leads to a more stable complex.
• What is the reaction when [Cu(H2O)₆]²⁺ reacts with EDTA^4-?


  [Cu(EDTA)]^2- and 6H₂O are produced.
• What is the significance of the stability of EDTA complexes?

  EDTA complexes can remove poisonous heavy metal ions and are used in shampoos to remove calcium ions.
• How do you calculate the concentration of copper(II) ions in a river water sample using EDTA titration?

  Concentration = moles of Cu²⁺ / volume of sample.
• What is the first step in calculating the concentration of copper(II) ions in the river water sample?

  Find moles of EDTA^4- using moles = concentration x volume.
• What is the second step in calculating the concentration of copper(II) ions in the river water sample?

  Use the balanced equation to find moles of Cu²⁺ from moles of EDTA^4-.
• What is the final step in calculating the concentration of copper(II) ions in the river water sample?

  Find concentration of Cu²⁺ in 25 cm³ using the formula concentration = moles / volume.
• What is the common shape of transition metal complexes with small ligands?

  Octahedral.
• What shape do transition metal ions form with larger ligands?

  Tetrahedral.
• What is the shape of square planar complexes?


  Square planar complexes have a square shape.
• What types of isomerism can complex ions show?

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

  Colour changes arise from changes in oxidation state, co-ordination number, or ligand.
• How does colour arise in transition metal complexes?

  Colour arises from electronic transitions between different d orbitals when visible light is absorbed.
• What happens when the ligand or coordination number changes in a complex?

  It alters the energy split between the d-orbitals, changing the frequency of light absorbed.
• What is the equation that links the energy difference between split d orbitals with the frequency of light absorbed?


  ΔE = hv
• What is Planck's constant?

  Planck's constant is 6.63 × 10^-34 J s.
• What is the speed of light?

  The speed of light is 3.00 × 10⁸ m/s.
• Why do compounds like Scandium and Zinc not exhibit colour?

  Scandium has no d electrons, and Zinc has a full d shell, so there is no energy transfer equal to visible light.
• What is the relationship between oxidation state and colour in transition metal complexes?

  Changes in oxidation state can lead to colour changes in transition metal complexes.
• How does the presence of ligands affect the energy levels of d orbitals?

  Ligands cause the 5 d orbitals to split into two energy levels.
• What happens to the colour of a complex when it absorbs light?

  The complex appears in the complementary colour of the light absorbed.
• What is the formula for the energy difference between split d orbitals in terms of wavelength?


  ΔE = hc/λ