Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Chemistry > alkenes > Flashcards

alkenes Flashcards

You may prefer our related Brainscape-certified flashcards:
Periodic Table flashcards Chemistry 101 flashcards AP® Chemistry flashcards Organic Chemistry 101 flashcards
1
Q

general formula of an alkene

A

CnH2n

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

functional group alkene

A

c=c

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

what is the double covalent bond a centre of

A

high electron density

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

unsaturated

A

contain one or more carbon-carbon double bonds

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

what is the shape around each carbon in the c=c double bond

A

triganol planar

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

what is the bond angle around each carbon in the c=c double bond

A

120

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

what forms when the p orbitals overlap in the c=c group

A

a pi bond

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

what does the presence of a pi bond create

A

restricted rotation about the planar c=c bond

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

how are alkenes named

A

like alkanes based on longest unbranched carbon chain with suffix ‘ene’

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

what must be indicated in alkenes with 4 or more carbon atoms in the longest chain

A

the position of the c=c bond

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

diene

A

2 c=c bonds

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

triene

A

three c=c bonds

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

what is the difference between open chain alkenes and cycloalkenes

A

cycloalkenes have 2 less hydrogen atoms than open chain alkenes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

how are cycloalkenes named

A

according to the largest ring containing the c=c bond

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

structural isomers

A

compound with same molecular formula but different structural formula

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

stereoisomers

A

compounds with the same structural formula but different arrangement of atoms in space

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

what type of stereoisomerism is exhibited by alkenes

A

E/Z isomerism

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

z

A

together

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

e

A

opposite

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

why does E/Z isomerism occur

A

as a result of restricted rotation about the c=c double bond

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

what must both carbon atoms of the c=c double bond be for an alkene to exhibit E/Z isomerism

A

both carbon atoms must be bonded to different groups

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

what are cycloalkanes

A

functional group isomers of alkenes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

how to determine whether an alkene is the E or Z isomer

A

identify the highest priority group on each C atom of the c=c double bond

if both highest priority groups are on same side- z isomer

if both highest priority groups are on opposite sides of C=c bond- E isomer

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

which atom has the highest priority

A

the atom with the highest atomic NUMBER

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

what happens if two atoms have the same atomic number

A

next atom n chain should be compared (first point of difference used to assign priority)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

why are alkenes reactive

A

high electron density of c=c double bond

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

what type of reactions do alkenes undergo

A

addition reactions in which a small molecule is added across C=C group

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

what does the addition reaction of an alkene form

A

a saturated molecule (pi bond breaks)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

electrophile

A

electron pair acceptor

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

why do alkenes react with electrophiles

A

electrophile are attracted to high electron density of C=C bond

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

what occurs during the reaction between alkenes and electrophiiles

A

covalent bonds broken and formed

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

what is produced as a result of the reaction between an electrophile and an alkene

A

a reactive positively charged intermediate called a carbocation

33
Q

what does a mechanism show

A

the breaking and forming of covalent bonds using curly arrows

34
Q

curly arrow

A

shows movement of pair of electrons

35
Q

where must curly arrows start from

A

a lone pair or a covalent bond

36
Q

what is the reagent in the reaction of alkanes with halogens

A

the halogen eg bromine

37
Q

what does the reaction between ethane and bromine produce

A

1,2- dibromo ethane

38
Q

what observations could be made during the reaction between ethene and bromine

A

bromine decolourises

39
Q

what is the name of the mechanism in the reacton between ethene and bromine

A

electrophilic addition

40
Q

what acts as the electrophile in the reaction between bromine and ethene

A

bromine

41
Q

what does the high electron density in the c=c group do

A

polarises the bond in the bromine molecule

42
Q

why does the br-br bond break

A

a pair of electrons is accepted by the delta plus br atom

43
Q

how does the br-br bond break

A

heterolytic fission

44
Q

what does the lone pair of electrons on the bromide ion form

A

a new c-br bond with the carbocation

45
Q

what is bromine used for

A

to test for the presence of a C=C group

46
Q

what is the reagent in the reaction of alkenes with hydrogen halides (same applies as halogen)

A

the hydrogen halide

47
Q

What do hydrogen halides contain

A

A permanent dipole, h atom always delta plus

48
Q

What is the reagent in the electrophilic addition reaction between sulphuric acid and lakebed

A

Concentrated sulphuric acid

49
Q

Organic hydrogen sulfates are readily hydrolysed with warm water to form…

A

An alcohol

50
Q

Hydrolysis

A

Breaking a bond using water

51
Q

What are carbocations classified as

A

Primary secondary or tertiary

52
Q

What is the classification of carbocations based on

A

The number of carbon atoms directly attached to the carbon with the positive charge

53
Q

What does a primary carbocation have

A

1 variable group

54
Q

What does a secondary carbocation have

A

2 variable groups

55
Q

What does a tertiary carbocation have

A

3 variable groups

56
Q

What do alkyl groups have a tendency to do

A

Release electrons

57
Q

What does the tendency of alkyl groups to release electrons help with

A

Stabilising the positive charge of carbocations- called the positive inductive effect

58
Q

What carbocations are the most stable and why

A

Tertiary as they have the most alkyl groups attached

59
Q

Order of stability of carbocations

A

Tertiary>secondary>primary

Most Least
stable Stable

60
Q

What does addition to an unsymmetrical Alkene produce

A

Two different organic products

61
Q

Major product

A

Produced in the largest amount

62
Q

Minor product

A

Produced in the smallest amount

63
Q

What is the yield of a particular product related to

A

The stability of the carbocation it is formed from

64
Q

What is produced when a hydrogen is added across a c=c bond

A

An alkane is produced (hydrogenation)

65
Q

What is hydrogenation used for

A

Important industrial process e.g. Production of margarine

66
Q

What catalyst is used in hydrogenation of alkenes

A

Nickel

67
Q

When are polymers formed

A

When monomers join together to form a very large molecule

68
Q

What do alkenesact as in addition reactions

A

Monomers, the c=c bond breaks allowing the monomers to add together

69
Q

Repeating unit

A

A specific arrangement of atoms that occurs in the structure over and over again

70
Q

What are simple polyalkenes

A

Unreactive

71
Q

What does the backbone of single c-c bonds make polyalkenes

A

Saturated

72
Q

What do the properties of polyalkenes depend on

A

Their structure and the intermolecular forces between neighbouring polymer chains

73
Q

What does polyethene have between neighbouring chains

A

VDW forces

74
Q

How can the properties of polymers like polyethene be modified

A

By increasing branching which decreases points of contact so the VDW forces are weakened- increased flexibility and lowers boiling point

75
Q

What is polychloroethene

A

Rigid and brittle

76
Q

What does polychloroethene contain

A

Polar c-Cl bonds and therefore has permanent dipole-dipole forces between polymer chains

77
Q

Addition of what molecules make polymers like polychloroethene more flexible

A

Plasticisers

78
Q

How do plasticisers make polychloroethene more flexible

A

They force neighbouring chains apart- allowing them to slide over each other

79
Q

Where do plasticisers go when added to polyalkenes like polychloroethene

A

Get in between neighbouring chains and reduce intermolecular forces

Chemistry (42 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions