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Organic Chemistry Chemistry of Carbon Compounds (except oxides, carbides, & carbonates)

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Presentation on theme: "Organic Chemistry Chemistry of Carbon Compounds (except oxides, carbides, & carbonates)"— Presentation transcript:

1 Organic Chemistry Chemistry of Carbon Compounds (except oxides, carbides, & carbonates)

2 Bonding Capacity H can form only 1 bond O and S like to form 2 bonds The halogens (F, Cl, Br, I) form only 1 bond N and P form 3 bonds

3 Why so many C compounds? Carbon atoms can bond with other carbon atoms in chains, rings, and networks covalentBonds are covalent

4 Lewis Diagram of C C Carbon has 4 unpaired electrons so it can form 4 covalent bonds

5 Properties of Covalent Substances molecular (also called molecular substances) Low melting & boiling points Poor conductors of heat & electricity May be soft or brittle Generally nonpolar – van der Waals forces Tend to dissolve in nonpolar solvents React more slowly than ionic compounds

6 Chemical Formulas show kind & number of atoms CH 2 Cl 2 CH 4 CH 3 OH CH 3 Cl

7 Structural Formulas Show kind & number of atoms Also show bonding patterns and approximate shapes of molecules 2-D rep of 3-D object so structural formulas aren’t totally realistic H H–C–H H

8 Structural Formulas – A single line represents one pair of electrons (a single bond) = A double line represents two pairs of electrons (a double bond) ●  A triple line represents three pairs of electrons (a triple bond)

9 Shape 4 unpaired electrons around C atom located at the corners of a tetrahedron 109.5  apart

10 Vocabulary HydrocarbonsHydrocarbons: organic compounds containing only C and H Homologous SeriesHomologous Series: – group of compounds with related structures and properties – each member of series differs from the one before it by adding one more unit

11 Vocabulary Interlude Saturated SSaturated: organic compounds containing only Single bonds UnsaturatedUnsaturated: organic compounds containing one or more double or triple bonds

12 Homologous Series The molecules have a fixed, numerical relationship among the numbers of atoms

13 Condensed Structural Formula Shows kind & number of atoms Shows some structural information, but not all the details structural formula: H H H CCC H–C–C–C–H H H H CCC becomes: CH 3 CH 2 CH 3

14 ALKANES C n H 2n+2

15 Alkanes Homologous series of saturated hydrocarbons Release energy when burned CH 4 H H–C–H H C 2 H 6 H H H–C–C–H H H

16 Alkanes (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

17 4 th straight-chain alkane C 4 H 10 H H H–C–C–C–C–H H H Or CH 3 CH 2 CH 2 CH 3

18 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

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20 Naming straight-chain Alkanes Name describes molecule so you can draw it aneaneAll alkanes have the suffix –ane The prefix depends on the number of C’s

21 10Dec 9Non 8Oct 7Hept 6Hex 5Pent 4But 3Prop 2Eth 1Meth # of C atomsPrefix

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

23 Properties of Alkanes Change systematically with number of C’s As the number of C’s increases, the boiling point increases –The molecules get heavier & harder to change into the gas phase

24 Properties of Alkanes Low Reactivity Except readily undergo combustion – fuels Nonpolar – Don’t dissolve well in water Low melting pts & boiling pts. (M.P. & B.P. increase with molecular mass) High vapor pressures

25 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

26 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 nonpolar coval cmpd: Bp depends on the strength of the van der Waals interactions (van der Waals forces ↑ as size of molecule ↑ - bigger molecule = bigger electron cloud)

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

28 Branched alkane: can’t link all the C’s without lifting pencil off paper Methyl propane

29 Isomers Compounds with same molecular formula but different structural arrangement The more C atoms there are the more isomers can have  more possible ways to arrange them

30 Isomers Different structures, different propertiesDifferent structures, different properties Isomers have different chemical and physical properties

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

32 ? same

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36 Naming Branched-Chain Alkanes The goal of the name is to describe the molecule so you can draw it

37 Naming branched-chain alkanes longest continuous chainFind longest continuous chain of C atoms –Bends don’t count! base namebase name derived from # of C’s in the continuous chain BranchesfirstBranches named first “yl” at end –count # C atoms & add “yl” at end assigning # to C attached to in the backbone# location of the branch by assigning # to C attached to in the backbone –# C's so get lowest number for branch more than one of the same type of branch: Use di, tri, etc.

38 H H–C–H H H–C–C–C–H H H H methyl Branch has 1 carbon – methyl Branch has to be at C-2 (Only give the number if necessary) Methyl propane C 4 H 10 CH 3 CH(CH 3 )CH 3 propane Longest continuous chain has 3 carbon atoms – propane

39 H H–C–H H H H H–C–C–C–C–H H H H H–C–H H Longest continuous chain has 6 hexane carbon atoms: it’s a hexane methyl Branch is 1 carbon long – methyl 2 Branch is located at C-2 2-methyl hexane C 7 H 16 CH 3 CH(CH 3 )CH 2 CH 2 CH 2 CH 3

40 A note about branches If you have several branches with the same # of C atoms, you can condense the name a little 2-methyl 3-methyl pentane becomes: –2,3-dimethyl pentane

41 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 carbon atoms: hexane Branch is 1 carbon long: methyl Branch is located at C-3 3-methyl hexane C 7 H 16 CH 3 CH 2 CH 2 CH(CH 3 )CH 2 CH 3 CH 3 (CH 2 ) 2 CH(CH 3 )CH 2 CH 3

42 Alkenes hydrocarbonsAnother homologous series of hydrocarbons one unsaturatedEach member contains at least one double covalent bond between C atoms  So alkenes are unsaturated General formula = C n H 2n

43 Naming Alkenes Names: # of C’s in parent chain gives prefix Suffix = -ene 1 st member is C 2 H 4: ethene H H C=C H H Alkenes with 4 or more C’s: Use # to show which C attached to

44 Naming Alkenes Number C atoms in backbone & give double bond the lowest possible number H H H C=C–C–C–H H H C 4 H 8 CH 2 CHCH 2 CH 3 H H H H H–C–C=C–C–H H H C 4 H 8 CH 3 CHCHCH 3 1-butene 2-butene

45 Naming Branched-Chain Alkenes Parent chain = longest chain that contains the double bond Also, position of double bond, not branches, determines numbering of backbone Give 1 st C in bond lowest possible #

46 Properties of Alkenes Nonpolar – low solubility in H 2 O Fairly low M.P. & B.P. More reactive than alkanes : –double bond = site of reactivity

47 Alkynes Homologous series of unsaturated hydrocarbons that contain one triple bond Each member contains one C≡C bond –Alkynes are unsaturated General formula = C n H 2n-2

48 Naming Alkynes Name: Prefix depends on # of C’s –Suffix = yne If necessary, number the 1 st carbon atom at which the triple bond occurs

49 H–C  C–HC 2 H 2 ethyne CHCH H H–C  C–C–H H H H H–C  C–C–C–H H H H–C–C  C–C–H H H C3H4C3H4 propyne CHCCH 3 C4H6C4H6 1-butyne CHCCH 2 CH 3 C4H6C4H6 2-butyne CH 3 CCCH 3

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51 3 Homologous Series of HC’s -yneC n H 2n-2 Alkynes -eneC n H 2n Alkenes -aneC n H 2n+2 Alkanes EndingGeneral FormulaName of Series

52 A.C 2 H 2 B.C 2 H 4 C.C 6 H 6 D.C 6 H 14 Which compound belongs to the alkene series? Correct answer = B. Alkenes follow the format C n H 2n A & C are C n H n, D is C n H 2n+2

53 A.C 2 H 2, C 2 H 4, C 2 H 6 B.C 2 H 4, C 3 H 4, C 4 H 8 C.C 2 H 4, C 2 H 6, C 3 H 6 D.C 2 H 4, C 3 H 6, C 4 H 8 In which group could the hydrocarbons all belong to the same homologous series? Correct answer = D Members of homologous series all have same relationship between atoms Every compound in set D fits the formula C n H 2n

54 A.Ethene B.Ethyne C.Propene D.Propane Which of the following is a saturated hydrocarbon? Correct answer = D The alkanes are saturated


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