1. AS Chemistry An Introduction to Alkanes

2. Alkanes are HYDROCARBONS because they contains ONLY CARBON and HYDROGEN atoms.

3. NameMolecular FormulaDisplayed FormulaSkeletal Formula Methane Ethane Propane Butane Pentane Hexane ALKANES General formula C n H 2n+2 CH 4 CH 3 CH 3 CH 2 CH 3 CH 3 CH 2 CH 2 CH 3 CH 3 CH 2 CH 2 CH 2 CH 3 CH 3 CH 2 CH 2 CH 2 CH 2 CH 3 CH H H H H H H CCH H H H H H C C H H CH H H H H H C C H H C H H CH H H H H H C C H H C H H C H H CH H H H H H C C H H C H H C H H C H H CH H H

4. NameMolecular Formula Boiling Point /K Methane Ethane Propane Butane Pentane Hexane CH 4 CH 3 CH 3 CH 2 CH 3 CH 3 CH 2 CH 2 CH 3 CH 3 CH 2 CH 2 CH 2 CH 3 CH 3 CH 2 CH 2 CH 2 CH 2 CH 3 109 185 231 273 309 342 Branched Isomer Boiling Point /K 2-Methylpropane CH 3 CH(CH 3 )CH 3 2-Methylbutane CH 3 CH(CH 3 )CH 2 CH 3 2-Methylpentane CH 3 CH(CH 3 )CH 2 CH 2 CH 3 261 301 333 Next slide for graphs

5. straight chain isomers 2-methyl branched isomers For similar molecular shapes, boiling point as relative molecular massbecause Van der Waal forces get as the number of electrons per molecule For molecules with same Mr, as the number of branches because Van der Waal forces get as the area of contact between molecules 2,2-dimethyl branched isomers boiling point

6. C C C C C C C C Greater contact between linear butane molecules  STRONGER van der Waal forces  HIGHER boiling point C C C C Lesser contact between branched methylpropane molecules  WEAKER van der Waal forces  LOWER boiling point C C C C

7. GENERAL REACTIVITY OF ALKANES Alkanes are generally very because the molecules are since C and H have Alkanes are also described as because they contain

8. The End