13.1.1

Explain the physical states (under standard conditions) and electrical conductivity (in the molten state) of the chlorides and oxides of the elements in period 3 in terms of their bonding and structure.

3

Include the following oxides and chlorides.

• Oxides: Na2O, MgO, Al2O3, SiO2, P4O6 and P4O10, SO2 and SO3, Cl2O and Cl2O7

• Chlorides: NaCl, MgCl2, Al2Cl6, SiCl4, PCl3 and PCl5, and Cl2

13.1.2

Describe the reactions of chlorine and the chlorides referred to in 13.1.1 with water.

2

13.2.1

List the characteristic properties of transition elements.

1

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.

3

13.2.3

Explain the existence of variable oxidation number in ions of transition elements.

3

Students should know that all transition elements can show an oxidation number 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.

1

13.2.5

Describe and explain the formation of complexes of d-block elements.

3

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.

3

Students need only know that, in complexes, the d sub-level splits into two sets of orbitals of different energy and the electronic transitions that take place between them are responsible for their colours.

13.2.7

State examples of the catalytic action of transition elements and their compounds.

1

Examples should include:

• MnO2 in the decomposition of hydrogen peroxide

• V2O5 in the Contact process

• Fe in the Haber process and in heme

• 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 Contact and Haber processes.

2

Aim 8