CHAPTER ELEVEN: UNSATURATED HYDROCARBONS Flashcards
What is an UNSATURATED HYDROCARBON?
Alkenes and Alkynes are families of hydrocarbons that contain double and triple bonds, respectively.
They are called UNSATURARED HYDROCARBONS because they do not contain the maximum number of hydrogen atoms as do alkanes.
What are SATURATED HYDROCARBONS?
UNSATURATED HYDROCARBONS react with hydrogen gas to increase the # of hydrogen atoms to become alkanes, which are SATURATED HYDROCARBONS.
ALKENES contain _______ bonds and share ____ pairs of valence electrons. In naming them, use the ending ______.
ALKYNES contain ______ bonds and share _____ pairs of valence electrons. In naming them, use the ending ______.
double; two; “end”
triple; three; “yne”
In any ALKENE, the double bond is RIGID, which means _____________.
there is no rotation around the double bond
When the hydrogen atoms are on the same side of the double bond, the structure is the _____ isomer.
When the hydrogen atoms are on the opposite sides of the double bond (across from each other), the structure is the _____ isomer.
Which is more stable?
cis isomer
trans isomer (trans means “across”)
In general, TRANS ISOMERS are more stable because the groups that are bigger than hydrogen atoms on the double bond are farther apart.
The most characteristic reaction of alkenes and alkynes is the _______ of atoms or groups of atoms.
Why does this occur?
The _______ reactions have different names that depend on _______________.
ADDITION
It occurs because double and triple bonds are easily broken, providing electrons to form new single bonds.
The ADDITION reactions have different names that depend on the type of reactant we add to the alkene or alkyne.
See Table 11.2 on page 395.
What is HYDROGENATION?
In a reaction called HYDROGENATION, H atoms add to each of the carbon atoms in a couple bond of an alkene or in the triple bond of an alkyne.
A catalyst is used to speed up the reaction.
The HYDROGENATION of ALKYNES requires _______ molecules of H2 to form the alkane product.
2
What is HALOGENATION?
Is a catalyst needed?
In the HALOGENATION reactions of alkenes, halogen atoms (such as chlorine or bromine) are added to the double bonds.
The reaction occurs readily without the use of a catalyst.
What is HYDRATION?
Is a catalyst needed?
Al alkene reacts with water (H-OH). A hydrogen atom (H) forms a bond with one carbon atom in the double bond, and the oxygen atom in OH forms a bond with the other carbon.
The reaction is catalyzed by a strong acid.
What is a POLYMER?
A large molecule that consists of small repeating units called MONOMERS
What is BENZYNE?
It consists of a ring of ______ carbon atoms with ______ hydrogen atom(s) attached to each carbon.
The family of BENZYNE compounds has become known as ________ compounds because many have a _______ odor.
Benzenes behave more like ________ (alkenes or alkanes?). It has the unique feature of _______________
a hydrocarbon with the molecular formula C6H6.
6; 1
Aromatic; fragrant
Alkanes. It has the unique feature of sharing 6 electrons equally among the 6 carbon atoms AND all the C-C bonds are identical.
When benzene has ________ substituent(s), the benzene ring is __________ (numbered or not numbered).
One; not
When benzene has 2 or more substituents, how is the benzene ring numbered?
The benzene ring is numbered to give the lower numbers to the substituents.
