Inorganic Chemistry: Metals and Their Compounds
Core concepts
Learn the reactivity series, the extraction of metals (electrolysis for reactive metals, reduction with carbon or carbon monoxide for less reactive ones), and the properties of key metal compounds. Focus on alkali and alkaline-earth metals (water reactions, oxide basicity, hydroxide solubility), aluminium (amphoteric oxide and hydroxide), iron (oxidation states +2 and +3, rusting), and copper (less reactive, used for electrical work). Understand why metals conduct and how alloys modify properties.
Traps that appear in questions
- Amphoteric behaviour: aluminium oxide and hydroxide react with both acids and alkalis; do not classify them as purely basic.
- Reactivity and extraction: only very reactive metals need electrolysis; moderately reactive metals use reduction.
- Iron oxidation states: Fe²⁺ (greenish, less stable) versus Fe³⁺ (yellow-brown, more stable in air); rusting requires both water and oxygen.
- Alkali metal reactions with water: they give the hydroxide and hydrogen, and reactivity increases down the group.
- Solubility trends: group 2 hydroxides become more soluble down the group; sulfates become less soluble.
Worked example
Why is aluminium extracted by electrolysis rather than by carbon reduction? Aluminium is high in the reactivity series, so carbon cannot reduce its oxide; electrolysis of alumina dissolved in molten cryolite is required.
Rule of thumb
Place the metal in the reactivity series first: it dictates the extraction method and the vigour of reactions with water and acids.