First-row d-block elements

Nature of science:

Looking for trends and discrepancies—transition elements follow certain patterns of behaviour. The elements Zn, Cr and Cu do not follow these patterns and are therefore considered anomalous in the first-row d-block. (3.1)

• Transition elements have variable oxidation states, form complex ions with ligands, have coloured compounds, and display catalytic and magnetic properties.
• Zn is not considered to be a transition element as it does not form ions with incomplete d-orbitals.
• Transition elements show an oxidation state of +2 when the s-electrons are removed.

Applications and skills:

• Explanation of the ability of transition metals to form variable oxidation states from successive ionization energies.
• Explanation of the nature of the coordinate bond within a complex ion.
• Deduction of the total charge given the formula of the ion and ligands present.
• Explanation of the magnetic properties in transition metals in terms of unpaired electrons.

Guidance:

• Common oxidation numbers of the transition metal ions are listed in the data booklet in sections 9 and 14.

• The properties and uses of the transition metals make them important international commodities. Mining for precious metals is a major factor in the economies of some countries.

Theory of knowledge:

• The medical symbols for female and male originate from the alchemical symbols for copper and iron. What role has the pseudoscience of alchemy played in the development of modern science?

Utilization:

• Syllabus and cross-curricular links:
• Topic 9.1—redox reactions
• Topic 10.2—oxidation of alcohols, hydrogenation of alkenes Option
• A.3—homogeneous and heterogeneous catalysis

Aims:

• Aim 6: The oxidation states of vanadium and manganese, for example, could be investigated experimentally. Transition metals could be analysed using redox titrations.
• Aim 8: Economic impact of the corrosion of iron.