1. ALKANES C n H 2n+2

2. Alkanes or C n H 2n+2 C 3 H 8 H H H H–C–C–C–H H H H CH 3 CH 2 CH 3 Chemical Formula Structural Formula Condensed Structural Formula

3. Alkanes: base unit CH 4 CH 3 CH 3 or C 2 H 6 CH 3 CH 2 CH 3 or C 3 H 8 CH 3 CH 2 CH 2 CH 3 or C 4 H 10 CH 3 CH 2 CH 2 CH 2 CH 3 or C 5 H 12 CH 2 Difference between each is CH 2

4. Properties of Alkanes Change systematically with number of C’s As number C’s increases, boiling point ↑ –molecules get heavier

5. Properties of Alkanes Low Reactivity –except readily undergo combustion – fuels Nonpolar – Don’t dissolve well in water Low mp’s & bp’s –mp & bp ↑ with ↑ molecular mass High vapor pressures –evaporate easily

6. A.Low melting point B.High melting point C.Soluble in polar solvents D.Insoluble in nonpolar solvents Which property is generally characteristic of an organic compound? Correct response = A

7. A.CH 4 B.C 2 H 6 C.C 3 H 8 D.C 4 H 10 Which of the following compounds has the highest boiling point? Correct answer = D bp depends on strength of forces holding molecules together [forces ↑as size of molecule bp depends on strength of forces holding molecules together [forces ↑as size of molecule ↑]

8. Naming Hydrocarbons

9. Naming straight-chain Alkanes Name describes molecule so can draw it aneaneAll alkanes have the suffix –ane prefix tells how many C’s

10. 10Dec 9Non 8Oct 7Hept 6Hex 5Pent 4But 3Prop 2Eth 1Meth # of C atomsPrefix

11. C 5 H 12 C 4 H 10 C3H8C3H8 C2H6C2H6 Meth + ane CH 4 NameFormulaEthanePropane Butane Pentane

12. Branched-chain alkanes Beginning with butane, C 4 H 10, more than 1 way to arrange the atoms H H–C–H H H–C–C–C–H H H H

13. Branched alkane - can’t link all C’s without lifting pencil off paper Methyl propane

14. Isomers Compounds with same molecular formula but different structural arrangement more C atoms  more isomers (more possible ways to arrange them)

15. Isomers Different structures = different propertiesDifferent structures = different properties –different chemical & physical properties

16. A note about isomers --- comparing 2 structural formulas: if can superimpose them, then not isomers = same molecule! If can rotate or flip one of structural formulas & superimpose it on the other, they are not isomers – they are same molecule!

17. These diagrams represent the same molecule Represents bond to H

18. These diagrams represent the same molecule

20. Two different molecules!

21. Naming Branched Hydrocarbons

22. Naming Branched-Chain Alkanes goal of name: describe molecule so can draw it

23. Naming branched-chain alkanes longest continuous chainfind longest continuous chain (backbone) of C atoms (Bends don’t count!) base namebase name derived from # C’s in longest chain branchesfirstbranches named first –Branches named by # C’s branchends in “yl” –“branch” name ends in “yl” assign#’s to C’s in backboneassign #’s to C’s in backbone # from end so lowest # given to branch more than 1 same type branch: –use di, tri, tetra

24. H H–C–H H H–C–C–C–H H H H methyl Branch: 1 carbon – methyl Branch at C #2: - can’t be on any other C so doesn’t need # propane Longest continuous chain has 3 carbon atoms = propane 12 3 Methyl propane C 4 H 10 CH 3 CH(CH 3 )CH 3

25. H H–C–H H H H H–C–C–C–C–H H H H H–C–H H hexane Longest continuous chain: 6 C’s = hexane methyl branch is 1 carbon long – methyl. 2 branch located at C #2 C 7 H 16 CH 3 CH(CH 3 )CH 2 CH 2 CH 2 CH 33 1 6 5 4 2 2-methyl hexane

26. A note about branches If several branches with same # C’s can condense name a bit 2-methyl 3-methyl pentane becomes 2,3-dimethyl pentane every branch must have a #

27. H H – C – H H H H H – C – C – C – C – H H H H–C–H H–C–H H H Longest continuous chain has 6 C’s: hexane -branch 1 C = methyl -branch located at C #3 C 7 H 16 CH 3 CH 2 CH(CH 3 )CH2CH 2 CH 3 3-methyl hexane