13.2 - The 'd' block elements
13.2.1 - List the characteristic properties of transition elements. Examples should include variable oxidation number, complex ion formation, existence of coloured compounds and catalytic properties.
13.2.2 - Explain why Sc and Zn are not considered to be transition elements.
13.2.3 - Explain the existence of variable oxidation number in ions of transition elements. Students should know that all transition elements can show an oxidation state of +2. In addition, they should be familiar with the oxidation numbers of the following: Cr (+3, +6), Mn (+4, +7), Fe (+3) and Cu (+1).
13.2.4 - Define the term ligand.
13.2.5 - Describe and explain the formation of complexes of d-block elements. Include: [Fe(H2O)6]3+, [Fe(CN)6]3-, [CuCl4]2-, and [Ag(NH3)2]+. Only monodentate ligands are required.
13.2.6 - Explain why some complexes of d-block elements are coloured. Students need only know that in complexes the d sub level splits into two sets of orbitals of different energy levels and that the electronic transitions that take place between them are responsible for their colours.
13.2.7 - State examples fo the catalytic action of transition elements and their compounds. Examples should include: MnO2 in the decomposition of hydrogen peroxide, V2O5 in the Contact process Fe in the Haber process, Ni in the conversion of alkenes to alkanes, Co in vitamin B12 Pd and Pt in catalytic converters. The mechanisms of action will not be assessed.
13.2.8 - Outline the economic significance of catalysts in the Haber and Contact processes. Aim 8.