2. Chapter Menu Hydrocarbons Section 21.1 Introduction to
Hydrocarbons Section 21.2 Alkanes Section 21.3 Alkenes and Alkynes
Section 21.4 Hydrocarbon Isomers Section 21.5 Aromatic Hydrocarbons
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slides. 3. Section 21-1 Section 21.1Introduction to
Hydrocarbons
- Explainthe terms organic compound and organic chemistry.
microorganism: a tiny organism, such as a bacterium or a
protozoan, that cannot be seen without a microscope
- Identifyhydrocarbons and the models used to represent
them.
- Distinguishbetween saturated and unsaturated hydrocarbons.
- Describewhere hydrocarbons are obtained and how they are
separated.
4. Section 21-1 Section 21.1Introduction to Hydrocarbons(cont.)
organic compound hydrocarbon saturated hydrocarbon Hydrocarbons are
carbon-containing organic compounds that provide a source of energy
and raw materials. unsaturated hydrocarbon fractional distillation
cracking 5. Section 21-1 Organic Compounds
- Chemists in the early 19th century knew living things produced
a variety of carbon compounds, called organic compounds.
- They were not able to synthesize them in the lab and labeled
them as mysterious.
- Whler was the first to produce an organic compound in the
lab.
6. Section 21-1 Organic Compounds(cont.)
- Organic compoundis applied to all carbon-containing compounds
with the primary exceptions of carbon oxides, carbides, and
carbonates, which are considered inorganic.
- In organic compounds, carbon nearly always shares its electrons
and forms four covalent bonds.
7. Section 21-1 Organic Compounds(cont.)
- Carbon atoms are bonded to hydrogen atoms or other elements
near carbon on the periodic table.
- Carbon atoms also bond to other carbon atoms and form long
chains.
8. Section 21-1 Hydrocarbons
- The simplest organic compounds arehydrocarbons , which consist
of only the elements carbon and hydrogen.
- There are thousands of hydrocarbons.
9. Section 21-1 Hydrocarbons(cont.)
- Carbon atoms bond to each other by single, double, and triple
bonds.
- Saturated hydrocarbonscontain only single bonds.
- Unsaturated hydrocarbons contain at least one double or triple
bond.
10. Section 21-1 Refining Hydrocarbons
- Many hydrocarbons are obtained from the fossil fuel
petroleum.
- Fractional distillation involves boiling petroleum and
collecting each group of components as they condense at different
temperatures.
11. Section 21-1 Refining Hydrocarbons(cont.) 12. Section 21-1
Refining Hydrocarbons(cont.)
- Fractional distillation towers do not yield fractions in
proportion to demand.
- Heavier fractions are converted to gasoline or other lighter
fractions by a process calledcracking .
13. Section 21-1 Refining Hydrocarbons(cont.)
- Gasoline is not a pure substance.
- Most molecules have 5 to 12 carbons.
- Gasoline is modified by adjusting its composition to improve
performance, resulting in the octane rating system.
14.
Section 21-1 Section 21.1 Assessment Petroleum is separated into
usable parts by boiling and condensing each component in a process
called ____.A. cracking B. fractional distillation C. saturation D.
bonding 15.
Section 21-1 Section 21.1 Assessment What is a hydrocarbon that
contains only single bonds called?A. unsaturated B. organic C.
saturated D. fully bonded 16. End of Section 21-1 17. Section 21-2
Section 21.2Alkanes
- Namealkanes by examining their structures.
IUPAC (International Union of Pure and Applied Chemistry):an
international group that aids communication between chemists by
setting rules and standards in areas such as chemical nomenclature,
terminology, and standardized methods
- Drawthe structure of an alkane when given its name.
- Describethe properties of alkanes.
18. Section 21-2 Section 21.2Alkanes(cont.) alkane homologous
series parent chain substituent group cyclic hydrocarbon
cycloalkane Alkanes are hydrocarbons that contain only single
bonds. 19. Section 21-2 Straight-Chain Alkanes
- Alkanesare hydrocarbons that have only single bonds between
atoms.
20. Section 21-2 Straight-Chain Alkanes(cont.)
- The names of alkanes end inane .
- Prefixes are derived from Greek numbers.
- A series of compounds that differ from one another by a
repeating unit is called ahomologous series .
21. Section 21-2 Straight-Chain Alkanes(cont.) 22. Section 21-2
Branched-Chain Alkanes
- Carbon atoms can bond to one, two, three, or four other carbon
atoms making a variety of chains possible.
23. Section 21-2 Branched-Chain Alkanes(cont.)
- Straight chains and branched chains can have the same molecular
formula.
- Order and arrangement of atoms in organic compounds determine
their identities.
- When naming branched chain alkanes, the longest continuous
chain of carbon atoms is called theparent chain .
- All the side branches are known assubstituent groups .
24. Section 21-2 Branched-Chain Alkanes(cont.) 25. Section 21-2
Branched-Chain Alkanes(cont.)
- Naming branched-chain alkanes
- Count the number of carbon atoms in the longest continuous
chain.
- Number each carbon in the parent chain.
- Name each alkyl group substituent.
- If the same alkyl group appears more than once as a branch on
the parent structure, use a prefix to indicate how many times it
appears.
- When different alkyl groups are attached to the same parent
chain, place their names in alphabetical order.
26. Section 21-2 Branched-Chain Alkanes(cont.)
- Naming branched-chain alkanes
- Write the entire name, using hyphens to separate numbers from
words and commas to separate numbers.
27. Section 21-2 Cycloalkanes
- An organic compound that contains a hydrocarbon ring is called
acyclic hydrocarbon .
- Cyclic hydrocarbons with only single bonds are
calledcycloalkanes .
28. Section 21-2 Cycloalkanes(cont.)
- Naming substituted cycloalkanes is the same as straight-chains
but with a few exceptions.
- The ring is always considered the parent chain.
- Numbering starts on the carbon that is bonded to the
substituent.
- When more than one carbon has a substituent, number in the
direction that gives the lowest possible numbers for the
substituents.
29. Section 21-2 Properties of Alkanes
- Structure affects molecular properties.
- Alkanes are not polar and are good solvents for other nonpolar
molecules.
30. Section 21-2 Properties of Alkanes(cont.)
- Physical properties of alkanes
- Compared to water, methane boils and melts and lower
temperatures.
- Methane molecules have little intermolecular attraction
compared to water.
31. Section 21-2 Properties of Alkanes(cont.)
- Chemical properties of alkanes
- Alkanes have low reactivity because they are nonpolar and have
no charge, and because they have strong single bonds between carbon
atoms.
32.
Section 21-2 Section 21.2 Assessment What is a cyclic alkane
with no substituents groups and 6 carbon atoms?A. heptane B.
cycloheptane C. cyclohexane D. cyclobutane 33.
Section 21-2 Section 21.2 Assessment Alkanes contain how many
double bonds? A. greater than 2 B. 2 C. 1 D. 0 34. End of Section
21-2 35. Section 21-3 Section 21.3Alkenes and Alkynes
- Comparethe properties of alkenes and alkynes with those of
alkanes.
hormone:chemical produced in one part of an organism and
transported to another part, where it causes a physiological
change
- Describethe molecular structures of alkenes and alkynes.
- Namean alkene or alkyne by examining its structure.
- Drawthe structure of an alkene or alkyne by analyzing its
name.
36. Section 21-3 Section 21.3Alkenes and Alkynes(cont.) alkene
alkyne Alkenes are hydrocarbons that contain at least one double
bond, and alkynes are hydrocarbons that contain at least one triple
bond. 37. Section 21-3 Alkenes
- Unsaturated hydrocarbons that contain at least one or more
double covalent bonds between carbon atoms are calledalkenes .
38. Section 21-3 Alkenes(cont.)
- Alkenes are named in much the same way as alkanes.
- When four or more carbon atoms are present, specify the
location of the double bond.
39. Section 21-3 Alkenes(cont.)
- When naming branched-chain alkenes, follow the same rules as
for alkanes, with two exceptions.
- The parent chain is always the longest chain that contains
double bond, whether it is the longest chain or not.
- The position of the double bond, not the branches, determine
the numbering.
- Use a prefix to designate thenumber of double bonds.
40. Section 21-3 Alkenes(cont.)
- Alkenes are nonpolar and have low solubility in water.
- Alkenes are more reactive than alkanes because the double bond
increases electron density between the two carbon atoms, providing
a good site for chemical reactivity.
41. Section 21-3 Alkynes
- Unsaturated hydrocarbons that contain one or more triple bonds
between carbon atoms are calledalkynes .
42. Section 21-3 Alkynes(cont.)
- Straight-chain and branched-chain alkynes are named in the same
way as alkenes, except the ending isyne .
43. Section 21-3 Alkynes(cont.)
- Alkynes have physical and chemical properties similar to
alkenes but are generally more reactive because the triple bonds
cause even larger electron densities than double bonds.
44.
Section 21-3 Section 21.3 Assessment Which of the following is
generally the most reactive?A. cycloalkanes B. alkanes C. alkenes
D. alkynes 45.
Section 21-3 Section 21.3 Assessment What is the name of a
straight-chain hydrocarbon with six carbon atoms and a triple bond
between the second and third carbon atoms?A. 2-hexene B. 3-hexene
C. 2-hexyne D. 3-hexyne 46. End of Section 21-3 47. Section 21-4
Section 21.4Hydrocarbon Isomers
- Distinguishbetween the two main categories of isomersstructural
isomers and stereoisomers.
electromagnetic radiation:transverse waves that carry energy
through empty space
- Differentiatebetween geometric isomers withcis-andtransprefixes
.
- Describethe structural variation in molecules that results in
optical isomers.
48. Section 21-4 Section 21.4Hydrocarbon Isomers(cont.) isomer
structural isomer stereoisomer geometric isomer Some hydrocarbons
have the same molecular formula but have different molecular
structures. chirality asymmetric carbon optical isomer optical
rotation 49. Section 21-4 Structural Isomers
- Isomers are two or more compounds that have the same molecular
formula but different molecular structures.
- Structural isomershave the same chemical formula but their
atoms are bonded in different arrangements.
50. Section 21-4 Structural Isomers(cont.)
- There are two main classes of isomers: structural isomers and
stereoisomers.
- Structural isomers have different physical and chemical
properties.
- The structure of a substance determines properties.
51. Section 21-4 Stereoisomers
- Stereoisomers are isomers in which all atoms are bonded in the
same order but are arranged differently in space.
52. Section 21-4 Stereoisomers(cont.)
- Geometric isomers result from different arrangements of groups
around a double bond.
- Cismeans on the same side, andtransmeans across from.
- Geometric isomers have different physical and chemical
properties.
53. Section 21-4 Stereoisomers(cont.) 54. Section 21-4
Chirality
- Louis Pasteur discovered two forms of crystallized tartaric
acid.
- The forms were mirror images of each other called right and
left-handed forms.
- The property in which a molecule exists inright and
left-handedforms is calledchirality .
55. Section 21-4 Optical Isomers
- Chirality occurs whenever a compound contains an asymmetric
carbon.
- Asymmetric carbonis a carbon atom that has four different atoms
or groups attachedto it.
- The four groups can be arranged in two different ways.
56. Section 21-4 Optical Isomers(cont.)
- Isomers that result from different arrangements of four
different groups around a carbon atom represent the other class of
stereoisomers, calledoptical isomers .
- Optical isomers have the same physical and chemical properties
except in chemical reactions where chirality is important.
57. Section 21-4 Optical Isomers(cont.)
- When polarized light passes through a solution containing an
optical isomer, the plane of polarization is rotated to the right
by the D-isomer and to the left by the L-isomer, producing and
effect calledoptical rotation .
58. Section 21-4 Optical Isomers(cont.) 59.
Section 21-4 Section 21.4 Assessment What are two molecules with
the same formula but different structures called? A. isotopes B.
chiral C. isomers D. asymmetric 60.
Section 21-4 Section 21.4 Assessment Which type of substances
have the same physical and chemical properties but produce
different optical rotations?A. isomers B. geometric isomers C.
isotopes D. optical isomers 61. End of Section 21-4 62. Section
21-5 Section 21.5Aromatic Hydrocarbons
- Compare and contrastthe properties of aromatic and aliphatic
hydrocarbons.
hybrid orbitals:equivalent atomic orbitals that form during
bonding by the rearrangement of valence electrons aromatic compound
aliphatic compound
- Explainwhat a carcinogen is, and list some examples.
Aromatic hydrocarbons are unusually stable compounds with ring
structures in which electrons are shared by many atoms. 63. Section
21-5 The Structure of Benzene
- Even by the middle of the 19th century, hydrocarbon ring
structures remained unknown.
- Michael Faraday first isolated benzene in 1825.
- Chemists knew the formula was C 6 H 6and proposed several
possible models which would have all be very reactive, but benzene
is unusually stable.
64. Section 21-5 The Structure of Benzene(cont.)
- German chemist Friederich Kekul claimed to have had a dream in
which he realized the flat, hexagonal shape ring structure for
benzene.
- Kekuls structure explained some of benzene's properties, but
not its lack of reactivity.
65. Section 21-5 The Structure of Benzene(cont.)
- Linus Paulings hybrid orbital theory explained benzenes lack of
reactivity.
- The double bonds in benzene are not fixed, but rather the
electrons are delocalized and shared among all six carbon
atoms.
66. Section 21-5 Aromatic Compounds
- Organic compounds that contain benzene rings as part of their
structure are calledaromatic compounds .
- Aromatic was originally used because many benzene related
compounds were found in pleasant smelling oils that came from
plants and plant parts.
67. Section 21-5 Aromatic Compounds(cont.)
- Aliphatic compoundsare the alkane, alkene, and alkyne
hydrocarbons, coming from the Greek word forfatbecause they were
obtained by heating animal fat.
68. Section 21-5 Aromatic Compounds(cont.)
- Substituted benzene compounds are named in the same way as
cyclic alkanes.
69. Section 21-5 Aromatic Compounds(cont.)
- Many aromatic compounds were commonly used as industrial and
laboratory solvents.
- Health risks linked to aromatics include respiratory ailments,
liver problems, and damage to the nervous system.
- Some aromatic compounds cause cancer.
70.
Section 21-5 Section 21.5 Assessment Aliphatic compounds were
originally obtained from ____.A. fossil fuels B. animal fats C.
plant oils D. minerals 71.
Section 21-5 Section 21.5 Assessment Which is NOT true of
benzene?A. It is an aromatic compound. B. It has a flat hexagonal
shape. C. The double bonds make itunstable. D. It has delocalized
electrons. 72. End of Section 21-5 73. Resources Menu Chemistry
Online Study Guide Chapter Assessment Standardized Test Practice
Image Bank Concepts in Motion 74. Study Guide 1 Section
21.1Introduction toHydrocarbons Key Concepts
- Organic compounds contain the element carbon, which is able to
form straight chains and branched chains.
- Hydrocarbons are organic substances composed of carbon and
hydrogen.
- The major sources of hydrocarbons are petroleum and natural
gas.
- Petroleum can be separated into components by the process of
fractional distillation.
75. Study Guide 2 Section 21.2Alkanes Key Concepts
- Alkanes contain only single bonds between carbon atoms.
- Alkanes and other organic compounds are best represented by
structural formulas and can be named using systematic rules
determined by the International Union of Pure and Applied Chemistry
(IUPAC).
- Alkanes that contain hydrocarbon rings are called cyclic
alkanes.
76. Study Guide 3 Section 21.3Alkenes and Alkynes Key
Concepts
- Alkenes and alkynes are hydrocarbons that contain at least one
double or triple bond, respectively.
- Alkenes and alkynes are nonpolar compounds with greater
reactivity than alkanes but with other properties similar to those
of alkanes.
77. Study Guide 4 Section 21.4Hydrocarbon Isomers Key
Concepts
- Isomers are two or more compounds with the same molecular
formula but different molecular structures.
- Structural isomers differ in the order in which atoms are
bonded to each other.
- Stereoisomers have all atoms bonded in the same order but
arranged differently in space.
78. Study Guide 5 Section 21.5Aromatic Hydrocarbons Key
Concepts
- Aromatic hydrocarbons contain benzene rings as part of their
molecular structures.
- The electrons in aromatic hydrocarbons are shared evenly over
the entire benzene ring.
79.
Chapter Assessment 1 Organic compounds must contain which
elements?A. carbon B. oxygen C. hydrogen D. nitrogen 80.
Chapter Assessment 2 Cyclohexane contains how many hydrogen
atoms?A. 6B. 12 C. 14 D. 20 81.
Chapter Assessment 3 Which of the following has the greatest
reactivity?A. benzene B. hexane C. hexene D. hexyne 82.
Chapter Assessment 4 A carbon bonded to four different groups is
____.A. cyclic B. aromatic C. asymmetric D. left-handed 83.
Chapter Assessment 5 Where were aromatic compounds originally
obtained from?A. fossil fuels B. plant oils, plant parts, and
spices C. animal fats D. minerals 84.
STP 1 Molecules that have the same formula and the atoms are
bonded in the same order but are arranged differently in space, and
have different properties are ____.A. structural isomers B.
geometric isomers C. optical isomer D. sterioisotopes 85.
STP 2 Ifnis the number of carbon atoms in a hydrocarbon, what is
the general formula of a cyclic alkane?A. C n H n+2 B. C n H 2n+2
C. C n H n D. C n H 2n 86.
STP 3 Which does NOT describe what happens as a liquid
freezes?A. The temperature of the systemis increased. B. Energy is
released by thesystem. C. The liquid is entering thesolid phase. D.
The molecules begin to forma lattice. 87.
STP 4 What is a series of compounds that differ from one another
by a repeating unit called?A. heterogeneous series B. homologous
series C. straight-chain series D. branched-chain series 88.
STP 5 What structural characteristic do all aromatic compounds
share? A. They are composed ofcyclohexane. B. They have a triple
bond. C. They contain a benzenering. D. They contain a
cyclicalkane. 89. IB Menu Click on an image to enlarge. 90. IB 1
91. IB 2 92. IB 3 93. IB 4 94. IB 5 95. IB 6 96. IB 7 97. IB 8 98.
IB 9 99. IB 10 100. IB 11 101. IB 12 102. IB 13 103. IB 14 104. IB
15 105. IB 16 106. IB 17 107. IB 18 108. IB 19 109. IB 20 110. IB
21 111. IB 22 112. CIM Table 21.5Examples of Alkenes Table
21.6Examples of Alkynes Figure 21.17Isomers of Pentane Figure
21.25Sigma- and Pi-bonding in Benzene 113. Help Click any of the
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