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Chapter 22

Chapter 22. Carbon and Hydrocarbons. Diamond and Graphite video. Carbon. Found in all living matter 95% of all known compounds contain carbon Carbon ranks 17 th in abundance in the earths crust Has 4 valence electrons Needs 4 more to become stable .

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Chapter 22

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  1. Chapter 22 Carbon and Hydrocarbons

  2. Diamond and Graphite video

  3. Carbon • Found in all living matter • 95% of all known compounds contain carbon • Carbon ranks 17th in abundance in the earths crust • Has 4 valence electrons • Needs 4 more to become stable

  4. Allotropes of Carbon • Diamond - colorless, crystalline solid - carbon atoms covalently bonded in a tetrahedral network -high melting point -used for cutting, drill bits, saw blades

  5. Graphite -soft black form -carbon atoms covalently bonded in layers of thin hexagonal plates -weak forces hold plates together so they slide off easily -fair conductor of electricity

  6. http://www.creative-chemistry.org.uk/molecules/structures.htmhttp://www.creative-chemistry.org.uk/molecules/structures.htm

  7. Fullerenes -found in the mid 1980’s in black soot from organic decay and burning -dark colored solid made of spherically network carbon atoms -more stable and harder than diamond at high pressure C60 = Buckminsterfullerene molecule(Bucky ball)

  8. Review: Ionic Bond: -electrostatic force that holds two ions together -transfer of electrons Characteristics: -high melting pts. -soluble in water -well defined crystals -aqueous solutions-conduct

  9. Covalent Bond: -shared pair(s) of electrons -elements in bond have nearly the same electronegativity number -non-metal w/ non-metal -can be polar (un-equal) or non-polar (equal) Characteristics: -low melting point, doesn’t conduct, brittle solids or gases or liquids

  10. Organic Chemistry • Study of carbon containing compounds excluding carbonates and oxides • Originally “study of chemistry of life” (Friedrich Wohler-found he could make the organic compound, urea, in the lab)

  11. Organic Covalent bonds Long chained molecules Decompose when heated Inorganic Ionic bonds or covalent bonds Short chains Phase change or vaporize when heated Organic vs. Inorganic

  12. Doesn’t dissolve readily in water Reactions proceed at a very slow rate Dissolves in water Reactions occur immediately as reactants are brought together

  13. 6. Reactions are greatly affected by reaction conditions (like catalysts, heat, changes in pressure) 6. Reactions follow known patterns (single displacement, synthesis, etc)

  14. Hydrocarbon • Simplest organic compound composed of hydrogen and carbon • Named with a set of prefixes and suffixes

  15. carbon -> meth- Carbons -> eth- -> prop- -> but- -> pent- -> hex- 7 carbons -> hept 8 -> oct- 9 -> non- -> dec- ->undecane- 20 -> eicosane Prefixes(stand for the # of carbons)

  16. Suffixes (tell type of bond) • ane (single bond) • ene (double bond) • yne (triple bond)

  17. Type of Formulas -molecular formulas ( #’s and letters) C4 H10 - structural formula (shows bonding arrangement) H H H H H— C— C— C— C— H H H H H

  18. condensed structural formula CH3—CH2—CH2—CH3

  19. Aliphatic compounds • Carbon atoms linked in chains

  20. Cyclic compounds • Carbon atoms linked in rings

  21. Alkanes • All single bonds • Also known as saturated hydrocarbons • Filled with as many hydrogens as possible • Form saturated fats • Have (-ane) ending • Soluble in non-polar solvents • Boiling pt. Increases as # of carbons increase • General Formula: CnH 2n +2 (n= # of carbons)

  22. C4 H? C 4 H 10

  23. Nomenclature (rules of naming)for Unbranched Alkanes • Count the number of carbons in the chain. • Find prefix for that # of carbons- this is the parent chain. • Add (-ane) ending. Ex. CH3—CH2—CH2—CH2—CH3 pentane

  24. Branched Alkane Rules(adding branches, changes properties of compound) • Find the longest continuous chain of carbons- this is the parent chain (determine the name as you did before) • Number the carbons starting on the end of the parent chain closest to the branch.

  25. The branch is a “Radical” molecule missing a Hydrogen atom • To name the radical- count carbons in radical, find prefix, add (-yl) ending CH3— methyl CH3 CH2— ethyl

  26. 5. Place the name of the radical (branch) b/4 the parent chain name. • Before the radical name, place the # of the carbon it is attached to. • If 2 or more “like” groups are in the chain, use prefixes (di-,tri-, tetra-) before the radical name with the #’s of the carbons they are attached to

  27. Ex. 2,3,4 trimethyl octane • Name radicals alphabetically when they are different Ex. 3-ethyl-4-propyl nonane

  28. Naming Cycloalkanes • single bonded ring compound • Place word (cyclo-) in front of parent name CH2 CH2 CH2 CH2 CH2 cyclopentane

  29. Cyclohexane cyclopropane

  30. CH3 CH3 1,3 -dimethylcyclohexane

  31. Isomers of Alkanes • Have same molecular formula but different shape and structure • Have same number of carbons and hydrogens • Isomers have different properties due to new shape Ex. Butane (2 isomers), pentane (3 isomers), hexane (5 isomers), decane (75 isomers)

  32. Pentane CH3—CH2—CH2—CH2—CH3 CH3—CH—CH2—CH3 2-methyl butane CH3 CH3 CH3—C—CH3 2,2 –dimethylpropane CH3

  33. Alkenes • Have at least one double bond • Unsaturated hydrocarbon (forms unsat. Fats) • Use (-ene) ending • General formula CnH 2n • More reactive than alkanes • Can’t rotate- due to double bond

  34. Naming Alkenes • Find the parent chain- longest chain that contains the double bond. • Number the carbons- starting on end closest to double bond • Find prefix, add (-ene) ending, place the number of the carbon the double bond starts on before the parent name

  35. CH3—CH=CH—CH2—CH2—CH3 Hexene 2-hexene

  36. Branched alkene • Find parent chain, number carbons starting on end closest to the double bond but including the branch. • Name and number the parent chain • Add the branch name and number before the parent chain # and name

  37. CH2=C—CH2—CH2—CH2—CH2—CH3 CH3 2-methyl-1-heptene

  38. More than one double bond use (-diene) or (-triene) CH3—CH=CH—CH=CH—CH3 2,4- hexadiene

  39. Geometric Isomers of Alkenes • Isomer in which the arrangement of the carbons and branches are the same but the angle is different at the double bond • Used for alkenes only • They differ in their geometry • Two types: cis and trans

  40. cis- isomer • Groups coming off the double bond are on the same side H H C = C CH3 CH3 cis-2-butene

  41. trans- isomer • Groups coming off the double bond are on opposite sides H CH3 C = C CH3 H trans-2-butene

  42. Alkynes • Unsaturated hydrocarbon • General formula Cn H 2n-2 • Very reactive • (-yne) ending

  43. Naming Alkynes • name like you name alkenes,except use (-yne) ending CH3 CH3—C C—CH—CH3 4- methyl-2-pentyne

  44. If you have both a double and a triple bond, the double bond takes precedence in numbering 1-pentene-4-yne CH2= CH - CH2 – C CH

  45. Aromatics • Constitutes a whole branch of chemistry • Rings with 6 carbons and 6 hydrogens and every other bond is a double bond • Parent chain = benzene , C6H6

  46. H C H – C C – H H – C C – H C H

  47. Naming aromatics • Parent chain is benzene • Number so a branch is on the number 1 carbon and then number the other branches so they are on the lowest number possible

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