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A level chemistry > 4.1 basic concepts and hydrocarbons > Flashcards

4.1 basic concepts and hydrocarbons Flashcards

1
Q

define saturated

A

compounds with only single bonds

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2
Q

Define functional group

A

A group of atoms that are responsible for the characteristic chemical reactions of a compound

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3
Q

What are the 8 functional groups

A

alkane
alkene
alcohol
aldehyde
carboxylic acid
haloalkane
ketone
alkyl

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4
Q

Describe an alkane

A

form a homologous series and are saturated hydrocarbons with the general formula CnH2n+2

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5
Q

define homologous series

A

Families of organic chemicals that have the same functional group and differ by a CH2 unit

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6
Q

Define aliphatic

A

in which the carbon atoms are joined in straight or branched chains or non-aromatic rings

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7
Q

Define alicyclic

A

carbon joined together in a non - aromatic ring structure
can be used interchangeably with aliphatic

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8
Q

Define aromatic

A

contains a benzene ring

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9
Q

describe an alcohol

A

CnH2n+1
-OH
hydroxy or -ol prefix

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10
Q

Describe an aldehyde

A

-CHO

C=O
I
H

suffix -al

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11
Q

Describe an alkene

A

CnH2n
contains a carbon double bond C=C
suffix -ene

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12
Q

Describe a carboxylic acid

A

CnH2n-1COOH
C=O
I
OH

suffix oic acid

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13
Q

Describe a haloalkane

A

they contain a halogen and have the prefix
fluoro
chloro
iodo
bromo

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14
Q

Describe a ketone

A

O
II
C
suffix -one

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15
Q

Define general formula

A

the simplest algebraic formula for a homologous series
e.g. CnH2n+2

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16
Q

Define displayed formula

A

shows the relative positions of the atoms and the bonds between them
e.g. stick diagrams

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17
Q

Define structural formula

A

provides minimum detail for the arrangement of atoms in a molecule
E.g. CH3CH3= C2H6

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18
Q

Define empirical formula

A

smallest whole number ratio of atoms of the element in a compound
e.g. CH2O =C6H12O6

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19
Q

Define molecular formula

A

shows numbers and types of atoms in a compound

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20
Q

Define skeletal formula

A

briefest way of representing molecules
/\/\ = pentane

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21
Q

define structural isomer

A

compounds with the same molecular formula but different structural formulae

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22
Q

describe chain isomerism

A

it is a structural isomer
It has a different arrangement of the carbon skeleton
These isomers have similar chemical properties but slightly different physical properties

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23
Q

Explain the correlation between carbon chain branching and boiling point

A

The greater the degree of branching the lower the boiling point because it decreases effectiveness of the intermolecular forces because they can’t be packed as closely so there are less points of contact and less energy is needed to break them apart

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24
Q

Describe position isomerism

A

It is a structural isomer
The molecule has the same functional group and carbon skeleton but the functional group is in a different position
Similar chemical properties but different physical properties

25
Q

Describe functional group isomerism

A

It is a structural isomer
Molecules have the same molecular formula but different functional groups therefore they also have different functional and chemical properties

26
Q

Give an example of a functional group isomer

A

Propanal - C3H6O
Propanone - C3H6O

27
Q

How would you work out empirical formula

A

Find the moles of the atoms in the compound and divide them by the lowest number of moles to get a ratio

28
Q

Define reaction mechanism

A

models that show movement of electron pairs during a reaction

29
Q

Define heterolytic fission

A

this occurs when a covalent bond breaks and both electrons go to one of the bonding atoms and produces ions

30
Q

Define homolytic fission

A

When a covalent bond breaks and each electron goes to a different bonded atom producing radicals

31
Q

Define radicals

A

Species with one or more unpaired electrons

32
Q

What are the steps in free radical substitution

A

Initiation - weakest bond is broken and radicals are generated

propagation - radicals are used and regenerated (2 steps)

Termination - radicals meet (3 steps)

33
Q

Give the equation for initiation during the reaction between methane and chlorine (homolytic fission)

A

Cl2—>2Cl•

34
Q

write the reaction mechanism for the propagation of the reaction between methane and chlorine

A

Cl• +CH4 —> CH3• + HCl
Cl2+ CH3• —> CH3Cl + Cl•

35
Q

Write the reaction mechanism for the termination step in the reaction between methane and chlorine

A

CH3• + CH3• —> C2H6
Cl• + Cl• —> Cl2
Cl• + CH3• —>CH3Cl

36
Q

Describe what is meant by multiple substitutions and give examples

A

Many side products may form if free radicals react with other chloromethane molecules
E.G.
CH3Cl + Cl• —> CH2Cl2
CH2Cl2 +Cl• —> CHCl3
ETC.

37
Q

Define what is meant by a sigma bond

A

It is formed between 2 carbons (in alkenes) using direct overlap of the electron clouds of 2 atoms

38
Q

Describe how a pi bond is formed

A

Formed by the electrons in the adjacent P-orbitals overlapping above and below the carbon atoms and is made after a sigma bond

39
Q

Define stereoisomer

A

Same molecular and structural formula but different arrangement of atoms in space

40
Q

What causes stereoisomers

A

Lack of rotation in c=c double bonds

41
Q

How does cis(z) isomerism differ from trans (e ) isomerism

A

Cis [z] when the highest priority groups are on the same side of the C=C bond

Trans [e] When the highest priority groups are on differing sides of the C=C bond

42
Q

Define electrophile

A

Electron pair acceptor

43
Q

Define nucleophile

A

Electron pair donor

44
Q

Define addition reaction

A

When 2 products react to form 1 product

45
Q

How do alkenes and alkanes differ in terms of reactivity

A

Alkenes are more reactive as the double bond is an area of high electron density which attracts electrophiles

46
Q

Define hydrogenation and the conditions

A

Addition reaction where hydrogen is added across the double bond
150C and a nickel catalyst

47
Q

Define hydration and the conditions required

A

Addition reaction between gaseous alkene and steam to make alcohol
300C
65atm
phosphoric acid catalyst

48
Q

Why are there two possible products when a hydrogen halide is added to an unsymmetrical alkene

A

Markownikoffs rule states that the H will go to the carbon atom with more hydrogens and this will influence carbocation stability as those with more alkyl groups attached to them are more stable.
The major product is the more stable one

49
Q

Why do alkyl groups influence carbocation stability

A

This is because alkyl groups push electrons towards the carbon ion and neutralises the charge stabilising it

50
Q

describe how polymer waste may be disposed

A

landfill
combustion
reusing
recycling
organic feedback

51
Q

describe landfills

A

large holes dug into the landscape which are lined to stop any contaminants from leeching into the soil or water table

rubbish is put in the holes and compacted and when it is full it is capped and landscaped

52
Q

What happens after rubbish is buried

A

the conditions change from normal to anaerobic and there is often a limited supply of water reducing the rate of decomposition of biodegradable material

many plastics are non-biodegradable and the waste does not break down and becomes a danger to wildlife

53
Q

describe combustion as a way to manage polymer waste

A

plastics are mainly organic so they can be burnt
As they contain large amounts of carbon their combustion releases large amounts of carbon dioxide or other polluting gasses such as HCl are made

Plastics have a high calorific value and can be burnt in power stations and the chemical energy can be transferred to drive turbines and generate electricity

54
Q

Describe how reusing can be used to manage polymer waste

A

plastics can be reused for their function many times such as a water bottle

55
Q

Describe recycling as a way to manage polymer waste

A

plastics need to be sorted into different types which is expensive and labour intensive

Plastics are cleaned and melted down into a new product

theres concerns about contamintation from last use

56
Q

Describe organic feedback as a way to manage polymer waste

A

after waste plastic has been sorted into many different types a series of chemical reactions can be used to break the plastic polymers into small organic molecules allowing recovered chemicals to be used in other reactions

57
Q

Describe biodegradable polymers

A

Plant starch is mixed with an additional polymer such as polyethene and given the starch breaks down itmakes the polymer chains smaller and the material biodegrades

however there is still concern about the small pieces of polymer

58
Q

describe photodegradable polymers

A

they break down chemically using energy with wavelengths similar to light as the bonds between the monomer units are weakened by absorption of light

However in landfills they may not be exposed to sufficient light

A level chemistry (14 decks)

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