Transition Metals

• What is the general property of transition metals?

  Incomplete d sub-level in atoms or ions
• What is the electron configuration of Scandium (Sc)?

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

  1s22s22p63s23p6 4s13d10
• Why is zinc not considered a transition metal?

  Zinc can only form a +2 ion
• What are the characteristics of transition metals?

  • Complex formation
  • Formation of coloured ions
  • Variable oxidation state
  • 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?

  Shared pair of electrons from one atom only
• What is the co-ordination number?

  Number of co-ordinate bonds to a metal ion
• What are monodentate ligands? Give examples.

  Ligands forming one coordinate bond; e.g., H2O, NH3
• What are bidentate ligands? Give examples.

  Ligands forming two coordinate bonds; e.g., C2O4
• What is the chelate effect?

  Stability increase when monodentate ligands are replaced
• 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?

  Leads to ligand substitution and coordination number change
• What is the shape of [CuCl4]2- complex?

  Tetrahedral
• What is the coordination number of [CoCl4]2- complex?

  4
• What is the role of EDTA in complex formation?

  Forms stable complexes with metal ions
• What is the significance of the chelate effect in complex stability?

  Increases stability due to higher entropy
• How do you calculate the concentration of copper(II) ions in river water?

  Use moles of EDTA and volume
• What is the formula to calculate moles of EDTA?

  moles = conc x vol
• What is the concentration of copper(II) ions in the river water sample?

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

  • Octahedral with small ligands (e.g., H2O, NH3)
  • Tetrahedral with larger ligands (e.g., Cl-)
  • Square planar (e.g., cisplatin)
  • Linear complexes (e.g., [Ag(NH3)2]+)
• What types of isomerism can complex ions exhibit?

  Cis-trans and optical isomerism
• What causes the colour changes in transition metal complexes?

  Changes in oxidation state, coordination number, or ligand
• How does light absorption relate to the colour of transition metal complexes?

  Light absorption promotes d electrons to higher energy levels
• What is the equation relating energy difference and frequency of light absorbed?

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

  1. 63 × 10–34 J s
• What is the speed of light value?

  1. 00 x 10^8 m s–1
• Why do Scandium and Zinc compounds lack colour?

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

  Changes from pink to yellow/brown
• What is the effect of changing ligands on the colour of a complex?

  Alters energy split between d orbitals
• What is the relationship between wavelength and energy difference in light absorption?

  ΔE = hc/λ
• What colour does a solution appear if it absorbs orange light?

  Blue
• What are the equations to learn regarding colour and light absorption?

  1. ΔE = hv
  2. ΔE = hc/λ
  3. v = frequency of light absorbed
  4. c = speed of light
  5. λ = wavelength of light absorbed
• What is the ion of Scandium in its ionic form?

  Sc$^{3+}$
• Why does Sc$^{3+}$ not transfer energy equal to visible light?


  It has no d electrons left to move
• Why do Zn$^{2+}$ and Cu$^{+}$ ions not transfer energy equal to visible light?


  Their d shell is full, no electron transfer
• In the equation [Co(H$_2$O)$_{6}$]$^{2+}$ + 6 NH$_{3}$ → [Co(NH$_{3}$)$_{6}$]$^{2+}$ + 6 H$_{2}$O, what is changing?


  Both ligand and coordination number
• What is the color change in the reaction involving cobalt complexes?

  Pink to yellow brown
• How does color arise in transition metal complexes?

  • Color arises from d-d transitions
  • Energy difference between split d orbitals
  • Absorption of specific wavelengths of light