Metals and Non-metals
What is tested
This domain examines physical and chemical properties of metals and non-metals, ionic bonding, the reactivity series, extraction of metals, corrosion and alloys. Numericals are rare, but equation writing and reasoning about reactivity are common.
Core rules
- Metals lose electrons to form positive ions; non-metals gain or share electrons. Metal oxides are generally basic; non-metal oxides are generally acidic.
- Reactivity series: K > Na > Ca > Mg > Al > Zn > Fe > Pb > H > Cu > Hg > Ag > Au. A metal above another displaces it from its salt solution.
- Extraction depends on reactivity: highly reactive metals by electrolysis; moderately reactive metals by reduction with carbon; unreactive metals occur native.
- Roasting heats a sulphide ore in air; calcination heats a carbonate ore in limited air.
- Corrosion is prevented by painting, oiling, galvanising or alloying. Alloys are mixtures with improved properties.
Worked example
Place a zinc strip in blue copper sulphate solution. Zinc is above copper in the reactivity series, so zinc displaces copper: Zn + CuSO4 → ZnSO4 + Cu. The blue colour fades and a reddish-brown deposit forms. Zinc is oxidised and Cu2+ is reduced.
Traps
Do not swap roasting and calcination. Graphite is a non-metal that conducts electricity. Mercury is a liquid metal. Sodium is stored in kerosene because it reacts with air and water. In electrolysis, oxidation occurs at the anode.