Chapter 3 - Structure And Stereochemistry Of Alkanes

Question 1

General formula of Alkanes

Answer 1

CnH2n+2

Question 2

A series of compounds that differ only in the number of methylene groups is known as ___________

Answer 2

Homologous series

Question 3

What does the prefix n mean in n-butane?

Answer 3

Short for normal, meaning straight chain

Question 4

What does the prefix iso- mean?

Answer 4

Methyl branch is on next-to-last carbon in the chain

Question 5

IUPAC Naming Rules

Answer 5

1. Find the longest continuous chain and use the name as the base
2. Number the longest chain beginning with the end of chain nearest a substituent
3. Name the groups attached to the longest chain as alkyl groups, give the location of each alkyl group by the number of the main chain carbon which it is attached (always in alphabetical order regardless of position)

Question 6

When there are two longest chains of equal length, use the chain __________

Answer 6

With the greatest number of substituents

Question 7

One carbon alkyl group

Answer 7

Methyl (-CH3)

Question 8

Two carbon alkyl group

Answer 8

Ethyl (CH3-CH2-)

Question 9

Three carbon straight chain alkyl group

Answer 9

Propyl group (CH3-CH2-CH2-)

Question 10

Isopropyl group

Answer 10

3 carbons, but a CH3 group is attached to the second carbon going upward

Question 11

Four carbon straight chain alkyl group

Answer 11

Butyl (CH3-CH2-CH2-CH2-)

Question 12

When two or more of the same substituents are present use ______

Answer 12

Prefixes (di-, tri-, tetra-)

Question 13

When two or more of the of the same alkyl substituents are present use prefixes but _________

Answer 13

Don’t use the prefixes while alphabetizing the names of the substituents

Question 14

Isobutyl group

Answer 14

CH3 group attached to the second carbon in a 3 carbon chain

Question 15

Sec-butyl group

Answer 15

CH3 group on the third carbon in a three carbon chain

Question 16

Tert-butyl group

Answer 16

Two CH3 groups on the second carbon in a 2 carbon chain

Question 17

Primary carbon

Answer 17

One substituent and two hydrogens attached

Question 18

Secondary carbon

Answer 18

Two substituents and one hydrogen attached

Question 19

Tertiary carbon

Answer 19

Three substituents attached to the carbon

Question 20

Methane has a hybridization of ___ and angles of ____

Answer 20

Sp3, 109.5 degrees

Question 21

Ethane has hybridization of ____ and rotation about the _____ sigma bond

Answer 21

Sp3, C-C

Question 22

______ are different arrangements of atoms caused by rotation about a single bond

Answer 22

Conformations

Question 23

Eclipsed conformation is ____ in energy

Answer 23

Highest

Question 24

Staggered conformation is _____ in energy

Answer 24

Lowest

Question 25

Gauche conformation has a ____ angle between the methyl groups

Answer 25

60 degree

Question 26

Totally eclipsed conformation is ____ in energy because ____ groups are in alignment

Answer 26

Highest, methyl

Question 27

Anti conformation occurs when the bond angle between CH3 groups are ________

Answer 27

180 degrees apart

Question 28

Anti conformations are ______ in energy

Answer 28

Lowest

Question 29

Steric strain occurs when

Answer 29

The two end methyl groups are so close together that their electron clouds experience a strong repulsion

Question 30

General formula of cycloalkanes

Answer 30

CnH2n

Question 31

When naming cycloalkanes if only one alkyl group is present, then ___________

Answer 31

No number is necessary

Question 32

In cycloalkanes cis means

Answer 32

Groups on the same face

Question 33

In cycloalkanes trans means

Answer 33

Groups on opposite faces

Question 34

Smaller rings demand bond angles _____ than 109.5 degrees, producing _______

Answer 34

Smaller, angle strain

Question 35

Torsional strain arises when _________

Answer 35

All bonds are eclipsed

Question 36

Heat of combustion is the

Answer 36

Amount of heat released when a compound is burned with an excess of oxygen in a sealed container

Question 37

Cyclic compounds with >= 4 carbons adopt ____________ to relieve ring strain

Answer 37

Nonplanar conformations

Question 38

The conformation of cyclopentane is slightly folded, like the shape of ___________

Answer 38

Open envelope

Question 39

The _____ conformation is the most stable conformational isomer of cyclohexane

Answer 39

Chair

Question 40

The chair conformation has no _____ strain or _____ strain

Answer 40

Torsional, angle

Question 41

“Flagpole” hydrogens ________

Answer 41

Project towards each other adding additional strain

Question 42

Axial bonds are directed ______ to the axis of the ring

Answer 42

Vertically parallel

Question 43

Equatorial bonds are directed ______ toward the equator of the molecule

Answer 43

Outward

Question 44

In chair-chair interconversion all axial substituents become _______ and vice versa

Answer 44

Equatorial

Question 45

In chair-chair interconversion all substituents pointing up originally ____________

Answer 45

Remain pointing up

Question 46

The axial substituent interferes with _______ on C3 and C5

Answer 46

Axial hydrogens

Question 47

Cis-1,3-dimethylcyclohexane can have both methyl groups in ____ or _____ positions

Answer 47

Axial, equatorial

Question 48

Trans-1,3-dimethylcyclohexane have ____ axial and ___ equatorial methyl groups

Answer 48

1,1

Question 49

Fused rings share _____ carbon atoms and the bond between them

Answer 49

Two adjacent

Question 50

Bridged rings share ______ carbon atoms and one or more carbon atoms between them

Answer 50

Two nonadjacent

Question 51

Spirocyclic compounds share __________

Answer 51

Only one carbons