Complete the electron arrangements for Ni and $\text{Ni}^{2+}$.
In an isolated transition metal atom or ion, the d orbitals all have identical energy. What term is used for orbitals with the same energy level?
Complete the diagram to illustrate the splitting of the d orbital energy levels in an octahedral complex ion.
On the axes below, sketch the shape of one d orbital from the lower energy level and one d orbital from the higher energy level.
The octahedral complex $[\text{Ni(H}_2\text{O)}_6]^{2+}$ appears green. Explain the source of the colour of this complex.
When $\text{NH}_3(aq)$ is added to the green solution containing $[\text{Ni(H}_2\text{O)}_6]^{2+}$, a grey-green precipitate, A, appears. On adding excess $\text{NH}_3(aq)$, this precipitate dissolves to form a blue-violet solution, B. Suggest formulae for A and B and write equations for the two reactions leading to A and B.