Chemistry of transition elements (A Level only): แบบฝึกหัด

A solution containing the complex ion \([Co(H_{2}O)_{6}]^{2+}\) is pink. When excess concentrated hydrochloric acid is added, the solution turns blue due to the formation of the \([CoCl_{4}]^{2-}\) ion.

Which statement correctly describes this change?

Zinc is a d-block element but is not classified as a transition element according to the IUPAC definition. Which statement best explains this based on the syllabus definition?

In an octahedral complex of a transition metal, the d-orbitals split into two sets of different energy. If a complex absorbs light with a frequency of \(6.00 \times 10^{14} \text{ Hz}\) to promote an electron between these d-orbitals, what is the value of the crystal field splitting energy, \(\Delta E\), for one mole of this complex?
(Use \(h = 6.63 \times 10^{-34} \text{ J s}\) and \(L = 6.02 \times 10^{23} \text{ mol}^{-1}\))

Which of the following describes the electronic configuration of a copper atom in its ground state, and the reason copper is classified as a transition element?

In an octahedral complex, the five d orbitals of the central metal ion are split into two groups of different energy levels, \(t_{2g}\) and \(e_{g}\).

Which set of d orbitals is promoted to the higher energy level in an octahedral field, and why?

Define the term ligand and state the type of bond formed between a ligand and the central metal ion in a complex.

In terms of electron configuration, explain why transition elements exhibit variable oxidation states, unlike group 1 elements.

Transition elements exhibit characteristic properties such as variable oxidation states, complex ion formation, and colour.

(a) Consider the \(Cu^{2+}\) ion. Write its electronic configuration and explain why copper is considered a transition element.

(b) Copper(II) ions form complex ions with water and ammonia. Describe the colours and formulae of the complex ions formed when aqueous ammonia is added dropwise, then in excess, to an aqueous solution containing \(Cu^{2+}\) ions. Explain these observations in terms of ligand exchange.

(c) Explain why transition metal complexes are typically coloured, referencing the splitting of d orbitals and the absorption of light.