Metal oxides

Metals react with oxygen to produce metal oxides. The reactions are oxidation reactions because the metals gain oxygen.

Students should be able to explain reduction and oxidation in terms of loss or gain of oxygen.

The reactivity series

When metals react with other substances the metal atoms form positive ions. The reactivity of a metal is related to its tendency to form positive ions. Metals can be arranged in order of their reactivity in a reactivity series. The metals potassium, sodium, lithium, calcium, magnesium, zinc, iron and copper can be put in order of their reactivity from their reactions with water and dilute acids.

The non-metals hydrogen and carbon are often included in the reactivity series.

A more reactive metal can displace a less reactive metal from a compound.

Students should be able to:
- recall and describe the reactions, if any, of potassium, sodium, lithium, calcium, magnesium, zinc, iron and copper with water or dilute acids and where appropriate, to place these metals in order of reactivity
- explain how the reactivity of metals with water or dilute acids is related to the tendency of the metal to form its positive ion
- deduce an order of reactivity of metals based on experimental results.

The reactions of metals with water and acids are limited to room temperature and do not include reactions with steam.

Extraction of metals and reduction

Unreactive metals such as gold are found in the Earth as the metal itself but most metals are found as compounds that require chemical reactions to extract the metal.

Metals less reactive than carbon can be extracted from their oxides by reduction with carbon.

Reduction involves the loss of oxygen.

Knowledge and understanding are limited to the reduction of oxides using carbon.

Knowledge of the details of processes used in the extraction of metals is not required.

Students should be able to:
- interpret or evaluate specific metal extraction processes when given appropriate information
- identify the substances which are oxidised or reduced in terms of gain or loss of oxygen.

Oxidation and reduction in terms of electrons

Oxidation is the loss of electrons and reduction is the gain of electrons.

Student should be able to:
- write ionic equations for displacement reactions
- identify in a given reaction, symbol equation or half equation which species are oxidised and which are reduced.