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A Level Chemistry > Module 4 - Chapters 11-13 P2 > Flashcards

Module 4 - Chapters 11-13 P2 Flashcards

1
Q

what are organic compounds?

A

Any compounds containing carbon

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2
Q

saturated hydrocarbons

A

single carbon-carbon bonds only (more saturated with hydrogen)

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3
Q

unsaturated hydrocarbons

A

one or more carbon-carbon double or triple bonds (less saturated with hydrogen)

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4
Q

compound with a triple bond

A

alkyne

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5
Q

general formula of alkane

A

CnH2n+2

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6
Q

general formula of alkyl

A

CnH2n+1

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7
Q

general formula of alkene

A

CnH2n

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8
Q

general formula of alcohol

A

CnH2n+1 OH

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9
Q

general formula of carboxylic acids

A

CnH2n O2

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10
Q

general formula of ketones

A

CnH2nO

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11
Q

definition of homologous series

A

A series of organic compounds having the same functional group but with each successive member differing by CH2

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12
Q

Functional group

A

part of the molecule largely responsible for the molecule’s chemical properties

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13
Q

what functional group does an amine group have?

A

NH2

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14
Q

name three classifications of hydrocarbons

A

aliphatic, alicyclic and aroMATic (not aroMANtic)

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15
Q

aliphatic hydrocarbons

A

carbon atoms arranged in chains (branched or unbranched)

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16
Q

alicyclic hydrocarbons

A

carbon atoms joined in a ring (cyclic) structure (branched or unbranched)

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17
Q

aromatic hydrocarbons

A

some or all of the carbon atoms are found in a benzene ring (C6H6)

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18
Q

general formula of alkyne

A

CnH2n-2

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19
Q

general formula of cycloalkane

A

CnH2n

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20
Q

prefix for naming carbon chain with 12 carbon atoms

A

Dodec

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21
Q

prefix for naming carbon chain with 20 carbon atoms

A

Eicos

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22
Q

functional group of aldehyde

A

CHO (O double bonded to C), functional group is always on carbon 1 for aldehydes

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23
Q

suffix (ending) for aldehydes

A

-al

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24
Q

functional group for ketones

A

C(CO)C (chain of 3 carbons and O double bonded to middle one)

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25
Q

suffix (ending) for ketones

A

-one

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26
Q

functional group for carboxylic acids

A

COOH (one O double bonded to C and one bonded as part of OH to carbon)

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27
Q

suffix (ending) for carboxylic acids

A

-oic acid

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28
Q

functional group for esters

A

COOC (one O double bonded to C, other O single bonded to two Cs)

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29
Q

suffix (ending) for esters

A

-oate

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30
Q

functional group for acyl chloride

A

COCl (O double bonded to C)

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31
Q

suffix (ending) for acyl chlorides

A

-oyl chloride

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32
Q

suffix (ending) for amines

A

-amine

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33
Q

functional group for nitriles

A

CN (N triple bonded to C)

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34
Q

suffix (ending) for nitriles

A

nitrile

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35
Q

molecular formula

A

shows the number and type of atoms of each element present in a molecule, doesn’t show the bonding

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36
Q

definition for empirical formula

A

the simplest whole-number ratio of the atoms of each element present in a compound

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37
Q

displayed formula

A

shows the relative positioning of all of the atoms in a molecule and the bonds between them, each line represents a pair of shared electrons

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38
Q

structural formula

A

shows the arrangement of the atoms in a molecule by showing clearly which groups are bonded together

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39
Q

skeletal formula

A

a simplified organic formula with all of the carbon and hydrogen labels removed along with any bonds to hydrogen atoms, this just leaves a carbon skeleton and any functional groups

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40
Q

definition of structural isomers

A

molecules with the same molecular formula but different structural formula

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41
Q

what are the three types of structural isomers?

A

chain, positional, functional group

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42
Q

chain isomerism

A

when the carbon atoms are moved on the original carbon chain to form structural isomers

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43
Q

positional isomerism

A

when the basic carbon skeleton remains unchanged but important groups (such as functional groups) are moved around on that skeleton

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44
Q

functional group isomerism

A

when molecules containing different functional groups have the same molecular formula, functional groups can be changed (e.g. ketones/aldehydes)

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45
Q

what are the components of crude oil?

A

petroleum gases, petrol (gasoline), kerosene (paraffin), diesel, lubricating oil, heavy fuel oil, bitumen

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46
Q

use of petroleum gases

A

used in domestic fuel

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47
Q

use of petrol/ gasoline

A

cars

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48
Q

use of kerosene/ paraffin

A

aircraft

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49
Q

use of diesel

A

cars

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50
Q

properties of small molecules in crude oil

A

low bpt, light in colour, easy to ignite, not viscous

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51
Q

properties of large molecules in crude oil

A

high bpt, dark in colour, difficult to ignite, thick/viscous if liquid (bitumen = solid at room temp)

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52
Q

why does increase in chain length in hydrocarbons in crude oil increase bpt?

A

london forces increase because more electrons are present and increasing chain length increases surface contact

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53
Q

why does branching of alkanes decrease bpt?

A
  • results in decreased points of surface contact between molecules so london forces decrease.
  • branching also prevents molecules packing together as easily so molecules are further away and intermolecular forces decrease
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54
Q

what type of covalent bond bonds each carbon in an alkane?

A

sigma bonds ( σ) , formed by the overlapping of orbitals with each overlapping orbital containing one electron

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55
Q

why is it not possible for alkanes to have stereoisomers?

A

the sigma bond allows free rotation of atoms around the molecule

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56
Q

why do alkanes have a low reactivity?

A
  • the sigma bonds are very strong (high bond enthalpy)
  • C-C bonds are non-polar
  • C-H bonds are considered non-polar due to the similar electronegativity of C and H
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57
Q

combustion

A

when alkanes react with oxygen to form carbon dioxide and water, heat is also produced

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58
Q

why are alkanes used as fuels?

A
  • readily available
  • easy to transport
  • easy to burn in a plentiful supply of oxygen without releasing toxic products
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59
Q

composition of natural gas

A

typically 80% methane with varying proportions of ethane, propane and butane

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60
Q

alkane which is a component of petrol

A

heptane

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61
Q

incomplete combustion

A

in a limited supply of oxygen, hydrogen atoms always oxidised to water but carbon may form carbon monoxide or soot (soot = singular carbon atoms)

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62
Q

carbon monoxide

A

colourless, odourless, highly toxic

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63
Q

what are the two types of fission to break covalent bonds?

A

homolytic and heterolytic fission

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64
Q

homolytic fission

A

each of the bonded atoms takes one of the shared pair of electrons from the bond, each atom becomes a radical so the products are the same

65
Q

radical

A

has a single unpaired electron

66
Q

diradical

A

has two unpaired electrons

67
Q

heterolytic fission

A

one of the bonded atoms takes both of the electrons from the bond, positive and negative ions are formed so the products are different

68
Q

name three types of reactions

A

addition, substitution, elimination

69
Q

addition reaction

A

two reactants join together to form one product

70
Q

substitution reaction

A

an atom or group of atoms is replaced by a different atom or group of atoms

71
Q

elimination reaction

A

the removal of a small molecule from a larger one, one reactant molecule forms two products

72
Q

photochemical reaction

A

alkanes react with halogens in the presence of UV light because the UV provides the initial energy for a reaction to take place

73
Q

name the stages of free radical substitution

A

initiation, propagation, termination

74
Q

initiation

A

a chlorine molecule is broken down into 2 free radicals by homolytic fission, a superscript dot alongside an atom shows it is a radical (no dot required for diradical)

75
Q

important point to remember about initiation

A

the products don’t have to be the same element - just the same type of radical

76
Q

propagation

A

chain reactions, one of the reactants and one of the products is always a free radical. always happens in two steps

77
Q

propagation reactions to learn

A

CH4 + Cl’ = CH3’ + HCl

CH3’ + Cl2 = CH3Cl + Cl’

(continued)

CH3Cl + Cl’ = CH2Cl’ + HCl
CH2Cl’ + Cl2 = CH2Cl2 + Cl’

(or the chlorine radical in step 2 could react with methane again as in step 1)

78
Q

termination

A

two radicals collide to form a molecule with all electrons paired, all free radicals are removed from the system

79
Q

problems with free radical substitution

A
  • further substitution can occur, may not result in the desired products
  • position of substitution cannot be controlled so a mixture of mono-substituted isomers will be formed
80
Q

how the products of further substitution can be controlled

A

using an excess of certain chemicals

81
Q

why do alkenes have lower bpts than alkanes?

A

double bond puts a kink in the chain so the chains cannot pack together as closely (decreasing surface contact so decreasing london forces)

82
Q

what is the other type of covalent bond (other than sigma) in alkenes?

A

pi bond, formed by the overlap of two p orbitals

83
Q

why is the pi bond weaker than the sigma bond?

A

electrons are further from the nucleus in the pi bond

84
Q

why can stereoisomers be formed with alkenes?

A

the pi bond restricts rotation of atoms around the molecule

85
Q

key point about double bonds and drawing in 3D

A

only counts as one area of electron density

86
Q

definition of stereoisomerism

A

when molecules have the same molecular and structural formulae but a different arrangement in space

87
Q

types of stereoisomerism

A

E-Z, cis-trans

88
Q

rules for E-Z isomerism

A
  • must have a C=C double bond

- different groups must be attached to EACH CARBON atom in the double bond

89
Q

Z isomers?

A

groups (same or with highest priority) on the same side of the molecule

90
Q

E isomers?

A

groups (same or with highest priority) on different sides of the molecule

91
Q

rules for cis-trans isomerism

A
  • must have C=C double bond

- two different groups must be attached to EACH CARBON but one of the groups must be hydrogen

92
Q

cis isomers?

A

hydrogen atoms on the same side of the molecule

93
Q

trans isomers?

A

hydrogen atoms on different sides of the molecule (diagonal)

94
Q

Cahn-Ingold-Prelog priority rule

A

priority is assigned to one of the groups on each carbon, two highest priority groups used to determine if E or Z.

  • ATOMS directly attached to the double bond are assessed for priority by highest atomic number,
  • if atomic numbers are the same then all atoms attached to that atom are listed from highest to lowest atomic number.
  • compare the lists element by element and the list with the element with the highest atomic number is given priority
  • double bonded atoms are counted twice in the list
95
Q

types of addition reactions with alkenes

A

hydrogenation, halogenation, hydration

96
Q

hydrogenation

A

hydrogen is added across the double bond, if enough hydrogen is present all of the double bonds are always broken. occurs with a nickel catalyst

97
Q

hydrogenation of unsaturated fats forming trans double bonds

A

formed during the process of the pi bond breaking and reforming

98
Q

unsaturated fats v saturated fats mpt

A

unsaturated fats have a lower mpt because they have a greater number of C=C bonds causing kinks in the chain so more difficult to pack together

99
Q

hydrogenation of vegetable oils

A

naturally-occurring vegetable oils in the cis configuration so more difficult to pack together due to kinks in the chain. mpt increases when hydrogenated so solidify, some cis isomers become trans

100
Q

halogenation

A

halogens added across a double bond, alkenes react with gaseous hydrogen halides to form haloalkanes

101
Q

testing for alkenes/unsaturation

A

bromine water added across double bond, de-colourises if added across double bond so if bromine water decolourises then double bond(s) are present (the molecule is unsaturated)

102
Q

hydration

A

alkenes react with steam to form alcohols in the presence of a phosporic acid catalyst or concentration sulfuric acid. the steam adds across the double bond, forming hydroxide groups to form an alcohol

103
Q

why are alkenes more reactive than alkanes?

A

the pi bond is weaker than a sigma bond

104
Q

what is electrophilic addition?

A

alkenes forming saturated compounds in addition reactions

105
Q

why do electrophiles attack the double bond in alkenes?

A

has high electron density due to electrons in pi bond

106
Q

definition of electrophiles

A

electron pair acceptors (usually a positive ion or slightly positive molecule)

107
Q

key points to remember about drawing the reaction mechanisms in electrophilic addition

A
  • curly arrows from the lone pair of electrons in the bond
  • bond breaks by heterolytic fission in non alkene molecule (e.g. HBr)
  • negative atom remaining = nucleophile
  • electrophile (hydrogen) hydrolyses the double bond
  • remaining carbon = carbocation (positive)
108
Q

nucleophile

A

attacks the carbocation (have an electron pair so opposite of electrophile)

109
Q

why are curly arrows used?

A

show movement of electrons, head of the arrow must point to where electrons will be when new bond formed

110
Q

rate of reaction of electrophilic addition as you go down group 17

A

rate of reaction increases because atomic radius increases so strength of hydrogen-halide bond decreases. less energy required to break bond so rate of reaction increases

111
Q

Markovnikoff’s rule

A

determines the major product (most abundant) of the two isomers formed. when a hydrogen halide reacts with an unsymmetrical (not the same on both sides) alkene the hydrogen attaches to the carbon with the greatest number of hydrogens

112
Q

types of carbocations in Markovnikoff’s rule

A

primary, secondary, tertiary

113
Q

primary carbocation

A

positive carbon only attached to one alkyl group (charge at end of chain)

114
Q

secondary carbocation

A

positive carbon attached to two other alkyl groups

115
Q

tertiary carbocation

A

positive carbon attached to three alkyl groups

116
Q

why Markovnikoff’s rule works

A
  • most stable carbocations are more abundant as products
  • secondary and tertiary carbocations are more stable because the positive charge can be decreased by the electrons on the alkyl groups.
  • electron-donating/ electron pushing effect
  • more alkyl groups = charge more spread out
117
Q

electron-donating/ electron pushing effect

A

alkyl groups have an electron-donating/ electron pushing effect away from them (to the carbocation) due to the other end of the bond attracting the electrons more strongly,
therefore the movement of electrons towards the positive charge decreases the charge and the charge becomes more spread out

118
Q

why are more stable carbocations more abundant as products?

A

less activation energy is required to form more stable carbocations so most of the mechanism occurs to form the most stable carbocations

119
Q

definition for activation energy

A

the minimum energy needed before a reaction will occur

120
Q

markscheme answer for explaining the most abundant carbocation formation

A

“The secondary (or tertiary) carbocation formed in this reaction is more energetically stable than the primary (or secondary) one which would be formed if the addition was the other way around, and so less activation energy is needed.”

121
Q

definition for polymerisation

A

an alkene (monomer) undergoing addition reactions with itself to form a polymer

122
Q

conditions required for polymerisation

A

200°C, 200atm, a small amount of oxygen free radical as an initiator

123
Q

definition for repeat unit

A

the specific arrangement of atoms in the polymer molecule that repeats over and over again

124
Q

difference between addition polymers and copolymers

A

addition polymers = one type of monomer

copolymers = two types of monomers in the same chain, alternating

125
Q

key point about drawing polymerisation equations

A

ALWAYS DRAW EVERYTHING VERTICALLY

126
Q

what type of bonds are between polymer chains?

A

london forces

127
Q

how are alcohols bonded in polymers?

A

hydroxyl groups bond by hydrogen bonding due to slight dipoles on oxygen and hydrogen. bonding of two hydroxyl groups together is stronger than a hydroxyl group and a hydrogen

128
Q

chain length determining properties of polymers

A

longer chains have stronger polymers as more london forces (more electrons)

129
Q

side groups determining properties of polymers

A

polar side groups (e.g. hydroxyl) form stronger attraction between chains

130
Q

branching determining properties of polymers

A

branching forms weaker polymers because can’t pack together as well, unbranched polymers = more crystalline and stronger.

stretching plastic organises chains more closely so temporarily stronger before intermolecular bonds broken

131
Q

cross-linking determining properties of polymers

A

increases mpt because chains more difficult to separate

132
Q

high density poly(ethene)

A

linear chains, strong, high density

133
Q

low density poly(ethene)

A

branched chains, weak, flexible, low density

134
Q

uses of poly(ethene)

A

plastic supermarket bags, shampoo bottles, children’s toys

135
Q

PVC

A

poly(chloroethene) aka poly(vinyl chloride)

136
Q

uses of PVC

A

gutters, records and windows

137
Q

uses of tetrafluoroethene

A

non-stick pans, electrical/cable insulation

138
Q

types of phenyl(ethene)

A

expanded, not expanded

139
Q

other name for phenyl(ethene)

A

poly(styrene)

140
Q

uses of expanded phenyl(ethene)

A

cups, packaging materials, thermal insulation

141
Q

uses of not expanded phenyl(ethene)

A

toys, yoghurt pots

142
Q

thermoplastics

A

no cross-linking, weak attraction between chains so low mpt, easy to mold when heating

143
Q

thermosets

A

extensive cross-linking, strong attraction between chains so polymer keeps shape upon heating

144
Q

methods of disposal of waste polymers

A
  • recycling
  • PVC recycling
  • combustion for energy production
  • feedstock recycling
145
Q

recycling +/-

A

+ conserves finite fossil fuels
+ decreases waste to landfill
- discarded polymers must be sorted by type (unusable if mixed)

146
Q

PVC recycling +/-

A
  • high chlorine content and additives present so disposal and recycling hazardous
  • releases HCl gas when burned (gas corrosive) and other pollutants (toxic dioxins) - can be removed from the waste gases by passing gas through alkali/carbonate
    + solvent reused
147
Q

recycling

A

sorted, chopped into flakes, washed, dried, melted, cut into pellets, used by manufacturers

148
Q

PVC recycling

A

solvents dissolve the polymer, PVC recovered from precipitation from solvent

149
Q

combustion for energy production +/-

A

+high stored energy level

-pollutants

150
Q

why can some polymers only be used in combustion?

A

polymers derived from petroleum/natural gas are difficult to recycle

151
Q

feedstock recycling +/-

A

+ able to handle unsorted and unwashed polymers

152
Q

what is feedstock recycling?

A

chemical and thermal processes to reclaim monomers/gas/oils from waste polymers, products = raw materials

153
Q

what are bioplastics?

A

produced from plant starch, cellulose, plant oils and protein. conserves oil reserves because not oil based

154
Q

what can be used as a starting material in the production of bioplastics?

A

sugar cane

155
Q

biodegradable polymers

A
  • broken down by microorganisms into water, CO2 and biological compounds
  • composed of starch or cellulose or contain additives to change polymer structure to be broken down by microorganisms
156
Q

compostable polymers

A

degrade and leave no visible or toxic residues

157
Q

alternative to alkene-based polymers

A

compostable polymers based on poly(lactic acid)

158
Q

examples of using compostable polymers

A
  • bags made from plant starch used as bin liners for food waste so bag and waste can be composted together
  • plates, cups and food trays made from sugar cane fibres to replace expanded polystyrene
159
Q

photodegradable polymers

A

a type of oil-based polymer used when plant-based alternatives aren’t possible.
contain bonds weakened by absorbing UV light to start degradation. light-absorbing additives could be added

A Level Chemistry (21 decks)

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