Metals, Non-metals and Organic Chemistry
Metals
The reactivity series ranks metals from potassium (most reactive) to gold (least). Metals above carbon are extracted by electrolysis; less reactive metals such as iron are reduced with carbon. More reactive metals displace less reactive ones from solutions. Alloys mix metals to improve properties, and rusting needs both oxygen and water. Metals are malleable, ductile and conduct heat and electricity.
Non-metals
Non-metals include oxygen, nitrogen, carbon, sulfur and chlorine. They are often poor conductors and form acidic oxides. Chlorine disinfects water; sulfur is used to make sulfuric acid; carbon exists as diamond, graphite and fullerenes with different structures.
Organic chemistry
Hydrocarbons contain only carbon and hydrogen. Alkanes have single bonds and the general formula CnH2n+2; alkenes have a C=C double bond and formula CnH2n. Alkenes decolourise bromine water; alkanes do not. Fractional distillation separates crude oil into fractions by boiling point. Cracking breaks large molecules into smaller, more useful ones. Alcohols contain –OH and carboxylic acids contain –COOH. Addition polymerisation joins alkene monomers.
Worked example
Methane burns completely: CH4 + 2O2 → CO2 + 2H2O. One carbon atom needs one CO2, four hydrogen atoms need two H2O, and the oxygen atoms balance with two O2 molecules. Incomplete combustion produces carbon monoxide, a poisonous gas.
Traps that cost marks
Do not confuse alkanes with alkenes; only alkenes decolourise bromine water. Displacement depends on reactivity, not mass. Alloys are mixtures, not compounds. Carbon monoxide is dangerous because it binds to haemoglobin.