4.1 Flashcards

1
Q

What do curly arrows represent ?

A

Flow of electron pairs during reaction mechanisms

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2
Q

What is a homologous series ?

A

Family of organic compounds that have same functional group but differ by CH2.

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3
Q

What is the bond angle of alkanes?

A

109.5

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4
Q

How does branching affect boiling point of alkanes ?

A

More branched=lower BP

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5
Q

Why does branching affect boiling point of alkanes?

A

More branches=molecules don’t fit together as neatly =fewer DD interactions

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6
Q

What are the 3 stages of radical substitution ?

A

1) initiation
2) propagation
3) termination

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7
Q

What is a pi bond formed by?

A

The electrons in adjacent p orbitals overlapping above+below atoms

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8
Q

what are aliphatic hydrocarbons?

A

where the carbon atoms are joined together in either straight or branched chains - NO BENZENE RING

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9
Q

what are alicyclic hydrocarbons?

A

where the carbon atoms are joined together in a ring structure but NO BENZENE RING

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10
Q

what are aromatic hydrocarbons?

A

where there’s at least 1 benzene ring in the structure

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11
Q

what are saturated compounds?

A

they contain only single covalent bonds between the carbons

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12
Q

what are unsaturated compounds?

A

contain at least one double carbon carbon bond.

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13
Q

what are structural isomers?

A

compounds with the same molecular formula but different structural formulae.

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14
Q

what are stereoisomers?

A

organic compounds which have the same structural formula but are arranged differently in space

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15
Q

what is homolytic fission?

A

when a covalent bond breaks and each electron goes to a different bonded atom, forming 2 radicals.

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16
Q

what is needed for homolytic fission to take place?

A

UV

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17
Q

what is heterolytic fission?

A

when a covalent bond breaks and both electrons go to one of the bonded atoms, forming oppositely charged ions.

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18
Q

what is the most stable carbocation?

A

TerTiary-when the carbon in the double bond is bonded to Three other carbons

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19
Q

what is the least stable carbocation?

A

PRIMARY=UNSTABLE- when the carbon in the double bond is bonded to 1 other carbon and 2 hydrogens

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20
Q

why are stereoisomers formed?

A

the RESTRICTED ROTATION of DOUBLE CARBON bonds

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21
Q

what has to happen for stereoisomers to exist?

A
  • double carbon

- each carbon in double bond has to have 2 different groups attached to it.

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22
Q

what is a molecular formula?

A

the number of atoms in one molecule of the element/compound - each element only appears once.

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23
Q

what is a sigma bond?

A

an overlap of orbitals between 2 atoms-all single bonds, free to rotate

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24
Q

what is an example of orbital hybridisation?

A

2s1 2p3 becoming 4 lots of sp3

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25
Q

what is orbital hybridisation?

A

the concept of mixing atomic orbitals into new hybrid orbitals (with different energies, shapes, etc., than the component atomic orbitals) suitable for the pairing of electrons

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26
Q

what does the graph between boiling point of alkanes and no of Cs in alkanes look like?

A

increases but increases less each time-levels off

27
Q

why does the graph between BP of alkanes and no of Cs look like how it looks?

A

the percentage of electrons you’re increasing the alkane by is shrinking each time, so there’s a smaller change in the induced dipole dipole forces.

28
Q

what is the trend in boiling points of alkanes?

A
  • increases with more Cs in formula

- straight chains have higher BPs than branched.

29
Q

why do straight chains have a higher boiling point?

A

they can get closer together, increasing surface contact between molecules (NOT SA) giving more induced dipole forces

30
Q

IF U DONT REVISE

A

u WILLflop

31
Q

why do alkanes have a low reactivity with many reagents?

A

1) they have high bind enthalpy

2) the sigma bonds have a very low polarity

32
Q

what are the 3 steps of homolytic substitution?

A

1) initiation
2) propagation
3) termination

33
Q

what are the problems of free radical substitution?

A
  • could go into wrong place on molecule-eg if you wanted 1-bromobutane but got 2-bromobutane
  • different product =s formed at termination step
  • multiple substitutions
34
Q

what is the overall equation for the breakdown of ozone?

A

03+0»» 202

35
Q

what are the propagation steps for the breakdown of ozone?

A
  • Cl + 03»» •ClO + 02

* ClO + 0»» •Cl + 02

36
Q

what is the general test for alkenes?

A

add bromine water- if it decolourises, it’s an alkene

37
Q

what is the general formula for the hydrogenation of alkenes?

A

alkene + hydrogen»> alkane

38
Q

what is hydrogenation of alkenes used for?

A

margarine manufacture

39
Q

what is the catalyst needed for hydrogenation of alkenes?

A

nickel

40
Q

what is the general equation for the hydration of alkenes?

A

alkene+water»» alcohol

41
Q

what is the catalyst for hydration of alkenes?

A

phosphoric acid

42
Q

what is the use of hydration of alkenes?

A

ethanol manufacture

43
Q

what is a structural isomer?

A

Compounds with the same molecular formula but different structural formula.

44
Q

what is homolytic fission?

A

breaking a covalent bond to form 2 radicals.

45
Q

what is heterolytic fission?

A

Breaking a covalent bond to form two oppositely charged ions.

46
Q

what is cis-trans isomerism?

A

A special case of E/Z isomerism in which two of the substituent groups attached to each carbon atom of the C=C group are the same.

47
Q

what is an electrophile?

A

An electron pair acceptor

48
Q

what is a structural isomer? (basic)

A

compounds with the same molecular formula but a different structural arrangement.

49
Q

name 4 ways to process waste polymers.

A

1) recycling
2) landfill
3) combustion
4) organic feedstock/cracked/production of plastics/new polymers

50
Q

what are 4 examples of a type of polymer being developed to minimise environmental damage?

A
  • biodegradable
  • compostable
  • soluble
  • photodegradable
51
Q

give 3 reasons why there are many organic products formed in radical substitution

A
  • multiple substitutions
  • different radicals joining together at termination step
  • termination steps can give products that will also react with bromine radicals.
52
Q

what is a functional group?

A

group of atoms that is responsible for for the reactions/that gives the chemical properties

53
Q

what is a radical?

A

something that has an unpaired electron.

54
Q

explain why some molecules show stereoisomerism

A

the carbon-carbon double bond is non rotating (1)

each carbon of the double bond is attached to 2 different groups.

55
Q

what are the problems of burning chlorine containing polymers?

A

produce toxic gases
produces HCl/acidic gas
produces dioxins
produces phosgene (?) (COCl2) (apparently it has respiratory effects)

56
Q

what are 3 ways polymers can be processed to reduce their environmental impact?

A

combustion TO PRODUCE ENERGY
sorting and recycling
cracked ( to give monomers)/chemical feedstock

57
Q

if they ask for a particular problem of burning a chlorine containing polymer, say…

A

it forms HCl
or
it forms chlorine

58
Q

where is the sigma bond’s electron density?

A

between bonding electrons

59
Q

where is the pi bond’s electron density?

A

above and below bonding atoms

60
Q

how do you get rid of HCl from the toxic gases formed when burning a chlorine hydrocarbon?

A

add sodium hydrogencarbonate which NEUTRALISES IT

61
Q

what is an alicyclic compound?

A

one that is both aliphatic and cyclic.

62
Q

how do you know when something’s an E isomer?

A

priority groups on opposite sides of each c.

63
Q

why do longer hydrocarbons have a higher melting point?

A

they have more SURFACE CONTACT so more induced dipole interactions.

64
Q

how do u word when something’s formed bc of the carbocation rule?

A

the carbocation intermediate is more stable.