Sketch the form of one $d$ orbital.
Finish the electronic configurations below. $\text{Ni}$: $1s^22s^22p^63s^23p^6\;\ldots$; $\text{Ni}^{3+}$: $1s^22s^22p^63s^23p^6\;\ldots$
Complete the diagram to show how ligands around an isolated transition metal ion change the energy of the $d$ orbitals.
Explain why transition metal complexes have colour.
$[\text{Cu}(\text{H}_2\text{O})_6]^{2+}$ is pale blue but $[\text{Cu}(\text{NH}_3)_4(\text{H}_2\text{O})_2]^{2+}$ is deep purple-blue. Suggest a reason for this.
The diagram shows the visible spectrum of a solution of $[\text{V}(\text{H}_2\text{O})_6]^{3+}$. State and explain what colour the solution is.
When chloride ions are present, $[\text{V}(\text{H}_2\text{O})_6]^{3+}$ reacts to give a mixture of isomeric octahedral complexes. $[\text{V}(\text{H}_2\text{O})_6]^{3+} + 2\text{Cl}^- \rightleftharpoons [\text{V}(\text{H}_2\text{O})_4\text{Cl}_2]^+ + 2\text{H}_2\text{O}$. Finish the three-dimensional diagrams to show the two isomers of $[\text{V}(\text{H}_2\text{O})_4\text{Cl}_2]^+$.
State the type of isomerism shown by isomer 1 and isomer 2 in (i).
The complex $[\text{V}(\text{H}_2\text{O})_6]^{3+}$ also reacts with ethane-1,2-diamine ($en$, $\text{H}_2\text{NCH}_2\text{CH}_2\text{NH}_2$) to give a mixture of isomeric octahedral complexes. $[\text{V}(\text{H}_2\text{O})_6]^{3+} + 3en \rightleftharpoons [\text{V}(en)_3]^{3+} + 6\text{H}_2\text{O}$ Complete the three-dimensional diagrams to show the two isomers of $[\text{V}(en)_3]^{3+}$. You may use a simplified symbol to represent $en$.
State the type of isomerism shown by isomer 1 and isomer 2 in (i).
The reaction of $[\text{Ni}(\text{H}_2\text{O})_6]^{2+}$ with aqueous ammonia forms the complex $[\text{Ni}(\text{NH}_3)_6]^{2+}$. $[\text{Ni}(\text{H}_2\text{O})_6]^{2+}(aq) + 6\text{NH}_3(aq) \rightleftharpoons [\text{Ni}(\text{NH}_3)_6]^{2+}(aq) + 6\text{H}_2\text{O}(l)$ Write the expression for $K_{\text{stab}}$ for $[\text{Ni}(\text{NH}_3)_6]^{2+}$.
$[\text{Ni}(\text{H}_2\text{O})_6]^{2+}$ also reacts with $en$ to form $[\text{Ni}(en)_3]^{2+}$. The values of the stability constants for the two complexes are shown: $K_{\text{stab}}\,[\text{Ni}(\text{NH}_3)_6]^{2+} = 4.8 \times 10^7\,\text{mol}^{-6}\,\text{dm}^{18}$ $K_{\text{stab}}\,[\text{Ni}(en)_3]^{2+} = 2.0 \times 10^{18}\,\text{mol}^{-3}\,\text{dm}^9$ A solution containing equal numbers of moles of ammonia and $en$ is added to $[\text{Ni}(\text{H}_2\text{O})_6]^{2+}$. State which complex is produced in the greater amount. Explain your answer.
When a limited amount of $en$ is added to $[\text{Ni}(\text{H}_2\text{O})_6]^{2+}$, the complex $[\text{Ni}(\text{H}_2\text{O})_2(en)_2]^{2+}$ is formed. Suggest how many stereoisomers of $[\text{Ni}(\text{H}_2\text{O})_2(en)_2]^{2+}$ are possible. Explain your answer. You are advised to include three-dimensional diagrams in your response.