Transition metals

Which factors affect the colour of a transition metal complex?

I. the oxidation state of the metal

II. the shape of the complex

III. the nature of the ligands

• I and II only

• I and III only

• I, II and III

• II and III only

Which factor explains why [Cu(NH₃)₄(H₂O)₂]²⁺ is a different colour to [Cu(H₂O)₆]²⁺?

• Ammonia has one non-bonding pair of electrons whereas water has two.

• Ammonia splits the d orbitals on the transition metal by a different amount to water.

• Ammonia transmits light of a different wavelength to water.

• Ammonia absorbs light of a different wavelength to water.

Which factor determines the order of the spectrochemical series?

• The charge on the ligands

• The ability of the ligands to split d orbitals

• The denticity of the ligands

• The number of non-bonding pairs of electrons on the ligands

Which factor explains why the splitting in the d orbitals in [Fe(H₂O)₆)]²⁺ is different to [Fe(H₂O)₆)]³⁺

• [Fe(H₂O)₆]³⁺ is more acidic than [Fe(H₂O)₆]²⁺.

• The oxidation state of iron is different in the two complexes.

• The two complexes have different shapes. 

• [Fe(H₂O)₆]²⁺ is oxidized by air in aqueous solution.

Which will form a colourless aqueous solution?

I. [Ti(H₂O)₆)]³⁺

II. [Sc(H₂O)₆)]³⁺

III. [Zn(H₂O)₆)]²⁺

• I and III

• II and III only

• I and II

• I, II and III

Which accounts for the fact that solid anhydrous copper(II) sulfate is white?

• The d sub level is not split.

• The d sub level is completely full.

• The energy emitted by the complex produces a continuous spectrum.

• White is the complementary colour of the colour absorbed when an electron is promoted from a lower to a higher orbital in the split d sub level.

Which factor accounts for the pink colour of [Mn(H₂O)₆]²⁺?

• Light with a wavelength corresponding to the colour pink is absorbed when an electron is promoted from a lower to a higher orbital in the split d sub level.

• Pink is the complementary colour of the colour absorbed when an electron is promoted from a lower to a higher orbital in the split d sub level.

• Pink is the complementary colour to the transmitted light.

• Light with a wavelength corresponding to the colour pink is emitted when an electron is demoted from a higher to a lower orbital in the split d sub level.

Cyanide ions are above water molecules in the spectrochemical series, i.e. H₂O < CN⁻. What changes will occur when cyanide ions replace all six water molecules in Fe(H₂O)₆]²⁺?

• The wavelength of light of the transition occurring when an d electron is promoted form a lower to a higher split d sub level will increase.

• The oxidation state of the iron will change form +2 to +3.

• The coordination number of the  complex will change.

• The splitting of the d orbitals will be greater.

The diagram shows the visible spectrum of a transition metal ion, [M(H₂O)₆]³⁺ and the colour wheel from Section 17 of the IB data booklet.

Which colour best describes an aqueous solution of this complex ion?

• yellow

• orange

• green

• violet

write the continuation of electronic configuration of Cu²⁺ ion

1s² 2s² 2p⁶ .................