3.3.2.0 basics

what are alkanes?

a homologous series of saturated hydrocarbons with the general formula: CnH2n+2

describe the reactivity of alkanes

they are very unreactive but they do burn in oxygen + react with halogens to produce halogenoalkanes

the alkanes are ______ molecules with…

• simple

• with weak van der Waals’ IMF

describe + explain the trend in the boiling points of straight chain alkanes

boiling points increase because

• as chain length increases, SA contact increases

• as SA contact increases, there are stronger VdWs forces between the molecules

describe + explain the trend in boiling points of isomers of eg C₅H₁₂

boiling points decrease because

• branched chain isomers have less SA contact between molecules

• therefore there are fewer (and so weaker) VdWs forces between the molecules