Inorganic Chemistry 2

Question 1

The Transition Metals- General Properties

Answer 1

• Good conductors of heat and electricity / hard, strong and shiny / high melting and boiling points
• Electronic configurations:
  Most will have 4s filled and partial 3d
  Cu=3d10 4s1
  Cr=3d5 4s1
  Electron configuration of an ion=minus/add charge from furthest away electrons
• Transition metals:
  Variable oxidation states
  Form coloured compounds
  Act as catalysts
  Partially filled d-shell
  Form complex ions

Question 2

Transition Metals- Complex Formation and The Shape of Complex Ions

Answer 2

• Coordinate bond=transition metal ions accept electron pairs from other ions/molecules
• Ligand=ion/molecule with lone pair electrons that forms coordinate bond with transition metal
• Complex ion=ligands bond to single transition metal ion
• Coordination number=number of coordinate bonds to ligands that surround transition metal ion
  Coordination 6=octahedral
  Coordination 4=tetrahedral / square planar
  (Chloride ion larger than ammonia/water so fewer ligands fit around central metal ion)
• Multidentate ligands=more than one atom with lone pair of electrons which bond to transition metal ion
  Hexadentate ligand(EDTA)=six atoms with lone pair
• Chelate effect=chelate complexes with polydentate ligands increase number of particles=increase in entropy which drives reaction to right=more favourable
• Isomers=same molecular and structural formula but different arrangement of atoms in space
• Geometrical isomerism=ligands in different position in space (E-Z)
• Optical isomerism=non-superimposable mirror images

Question 3

Transition Metals- Coloured Ions

Answer 3

• Why transition metal complexes coloured:
  Partially filled d-orbitals
  Electrons move from one d-orbital to another
  In compounds, presence of other atoms=d-orbitals different energies
  When electrons move to higher d-orbital=absorb energy in region of spectrum equal to difference in energy between levels
  Colour missing from spectrum so only see combo of colours not absorbed
• ΔE=hv
  Energy / frequency / Planck’s constant
  Frequency related to colour of light
• Colorimetry=measures amount of light of wavelength that passes through coloured solution
  More conc=less light transmitted

Question 4

Transition Metals- Variable Oxidation States

Question 5

Transition Metals- Catalysis

Answer 5

• Catalyst=speeds up rate of chemical reaction without being used up- alternative reaction pathway
• Heterogenous catalysts=different phase than reactants
• More efficient:
  Increase surface area
  Spread catalyst onto inert support medium
• Example=Haber process:
  N2+3H2 -> 2NH3
  Iron catalyst
• Example=Contact process:
  2SO2+O2 -> 2SO3
  SO2+V2O5 -> SO3+V2O4
  2V2O4+O2 -> 2V2O5
  Vanadium(V)oxide catalyst
• Homogenous catalysts=same phase as reactants
• Example=
  S2O82-+2Fe2+ -> 2SO42-+2Fe3+
  2Fe3++2I- -> 2Fe2++I2
  Fe2+ catalyst
• Autocatalysis=product is catalyst
  Starts slowly then speeds up then slows down as reactants used up