Brainscape's Knowledge GenomeTM

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


See full index

Chemistry > properties of alkene > Flashcards

properties of alkene Flashcards

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

Why do double bonds make alkenes reactive

A

sigma have a high electron density
Pi bond has a relatively low bond enthalpy
Easy to break, more reactive

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

What is different about cycloalkenes

A

Have 2 fewer hydrogens

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

What do double bonds contain

A

Pi bond and sigma bonds

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

When do sigma bonds happen

A

When 2 s orbitals overlap.

They align horizontally to give a single covalent bond

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

Sigma bond properties

A

Strong electrostatic force of attraction between nuclei and shared pairs of electrons due to high electron density between nuclei
Has a high bond enthalpy

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

What are pi bonds

A

Parallel overlap of 2 p orbitals above and below the bonding c atoms

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

Why are pi bonds weaker than sigma bonds

A

Electron density is spread out above and below the nuclei. The electrostatic attraction is weaker so they have a weaker bond enthaply making them more reactive

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

Why are alkanes less reactive

A

Only have sigma bonds

They are non polar

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

What are alkenes good for

A

Polymers and petrochemicals

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

Why are alkenes open to attack from electrophiles

A

Pi bond sticks out a little and the whole double bond has a high electron density
Electrophile adds to the molecule

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

What does stereoisomerism occur on

A

Alkenes
contain double bond
Atoms cant rotate around the double c bond and is rigid

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

Stereoisomers meaning

A

Same structural formula but the different arrangement in atoms

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

What are electrophiles

A

Electron pair acceptor

Deficient in electrons

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

Example of electrophiles

A

delta positive polar bonds, positive ions

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

Test for alkenes

A

Bromine water - orange to colorless

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

electrophilic addition hydrogen gas with ethene conditions

A

150 degrees, nickel catalyst,

make ethane

17
Q

What does the hydration of alkenes make

A

alcohol

18
Q

hydration of alkene conditions

A

steam and acid catalyst

19
Q

What do alkenes reacted with hydrogen halides make

A

halogenoalkanes

20
Q

Landfill is useful for disposing plastics that

A
  • are too difficult to recycle
  • Too difficult to separate from other materials
  • Not enough plastic to extract it
21
Q

Why is it hard to dispose of polymers

A

Not biodegradable

22
Q

what recycled plastic can be used for

A

plastics cracked into monomers and used as an organic feedstock for plastic or other substances
Some plastics can be remoulded

23
Q

When is incineration used to dispose of plastic

A

plastic cant be recycled

energy from burning used to generate energy

24
Q

Why is burning plastic bad

A

Can release toxic fumes
Chlorine-based plastics produce harmful HCL gas when burned.
Flue gas scrubbers used to neutralise acidic gases by firing a base

25
Q

what does biodegradable polymers need to biodegrade

A

good supply of oxygen and moisture

Light and water so microorganisms can digest

26
Q

what are biodegradable polymers made from

A

oil fractions and renewable sources

More expensive than non-biodegrable plastics

27
Q

Benfit to environment of biodegradable polymers

A

Less land use, decompose

Can be made from renewable materials reducing dependency in crude oil

28
Q

What is needed to break down photodegrable polymers

A

Light

29
Q

Why does bromine water go orange to colourless in presence of alkenes

A

Will undergo an electrophilic addition reaction due to the double c bond

30
Q

Shape of alkenes

A

trigonal planar

31
Q

Why the shape of an alkene trigonal planar

A

3 regions of electron density around each carbon atom
Electrons repel each other
All of the atoms are in the same plane

32
Q

Why are alkenes so rigid

A

Position of the pi bonds electron density above and below the plane of the sigma bond

33
Q

When do cis-trans isomers occur

A

One of the attached group on each carbon atom on the double bond must be hydrogen.

34
Q

What is carbocation

A

Positively charged carbon atom

35
Q

Why is tertiary carbocation the most stable

A

The more alkyl group attached to the positively charged carbon atom the more the charge is spread out making the ion more stable

Chemistry (24 decks)

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