1. Chapter 22 Hydrocarbon Compounds 22.2 Unsaturated Hydrocarbons
22.3 Isomers
22.4 Hydrocarbon Rings
22.5 Hydrocarbons from Earth’s Crust
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2. What does it mean if a fat is unsaturated?
CHEMISTRY & YOU
What does it mean if a fat is unsaturated?
For example, olives are high in unsaturated fat but low in saturated fat.
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3. Alkenes What are the structural characteristics of alkenes? Alkenes
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4. Alkenes
An organic compound that contains the maximum number of hydrogen atoms per carbon atom is called a saturated compound.
Alkanes are saturated compounds because the only bonds in alkanes are single covalent bonds.
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5. Alkenes
An organic compound that contains double or triple carbon-carbon bonds is called an unsaturated compound.
The ratio of the hydrogen atoms to carbon atoms is lower in an unsaturated compound than in a saturated compound.
An alkene is a hydrocarbon that contains one or more carbon-carbon double covalent bonds.
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6. Alkenes
At least one carbon-carbon bond in an alkene is a double covalent bond. Other bonds may be single carbon-carbon bonds and carbon-hydrogen bonds.
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7. Ethene (C2H4) is the simplest alkene.
Alkenes
Ethene (C2H4) is the simplest alkene.
It is often called by the common name ethylene.
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8. This chain is the parent alkene.
Alkenes
To name an alkene by the IUPAC system, find the longest chain that contains the double bond.
This chain is the parent alkene.
It has the root name of the alkane with the same number of carbons plus the ending -ene.
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9. Alkenes
The chain is numbered so that the carbon atoms of the double bond have the lowest possible numbers.
Substituents on the chain are named and numbered in the same way they are for alkanes.
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10. What is the difference between propene and propane?
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11. What is the difference between propene and propane?
Propene is an alkene with three carbons and one carbon-carbon double bond. Propane is an alkane with three carbons and no carbon-carbon double bonds.
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12. Describe how saturated and unsaturated fats differ structurally.
CHEMISTRY & YOU
Describe how saturated and unsaturated fats differ structurally.
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13. Describe how saturated and unsaturated fats differ structurally.
CHEMISTRY & YOU
Describe how saturated and unsaturated fats differ structurally.
An unsaturated fat is a fat that contains double or triple carbon-carbon bonds.
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14. Alkynes What are the structural characteristics of alkynes? Alkynes
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15. Alkynes
A hydrocarbon that contains one or more carbon-carbon triple covalent bonds is called an alkyne.
A carbon-carbon triple bond is shown in structural formulas as three parallel lines.
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16. Like alkenes, alkynes are unsaturated compounds.
At least one carbon-carbon bond in an alkyne is a triple covalent bond. Other bonds may be single or double carbon-carbon bonds and carbon-hydrogen bonds.
Like alkenes, alkynes are unsaturated compounds.
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17. Alkynes are not plentiful in nature.
The simplest alkyne is the gas ethyne (C2H2), which has the common name acetylene, and is shown at left.
The triple bond restricts rotation in an ethyne molecule, which has a linear shape.
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18. Alkynes
Like alkanes, the major attractions between alkenes and alkynes are weak van der Waals forces.
Boiling point (ºC)
–20
–40
–60
–80
–100
–120
As a result, the introduction of a double or triple bond into a hydrocarbon does not have a dramatic effect on physical properties such as boiling point.
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19. What is the difference between ethene and ethyne?
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20. What is the difference between ethene and ethyne?
Ethene is an alkene containing two carbons in a carbon-carbon double bond. Ethyne is an alkyne containing two carbons in a carbon-carbon triple bond.
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21. Key Concepts
At least one carbon-carbon bond in an alkene is a double covalent bond. Other bonds may be single carbon-carbon bonds and carbon-hydrogen bonds.
At least one carbon-carbon bond in an alkyne is a triple bond. Other bonds may be single or double carbon-carbon bonds and carbon-hydrogen bonds.
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22. Glossary Terms
saturated compound: an organic compound in which all carbon atoms are joined by single covalent bonds; it contains the maximum number of hydrogen atoms per carbon atom
unsaturated compound: an organic compound with one or more double or triple carbon-carbon bonds
alkene: a hydrocarbon containing one or more carbon-carbon double bonds; alkenes are unsaturated hydrocarbons
alkyne: a hydrocarbon containing a carbon-carbon triple bond; alkynes are unsaturated hydrocarbons
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23. END OF 22.2
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