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A Level chemistry Y12 > 3.3.1. Formulae, isomerism and mechanisms > Flashcards

3.3.1. Formulae, isomerism and mechanisms Flashcards

1
Q

What is an empirical formula?

A

The simplest whole number ratio of atoms of each element in a compound

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2
Q

What is a molecular formula?

A

The formula that shows the actual number of atoms of each element in a molecule

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3
Q

What is a general formula?

A

A generalised formula which enables you to work out the molecular formula of a compound within a homologous series

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4
Q

What is a structural or shorthand formula?

A

A formula showing the arrangement of atoms in a substance without showing the bonds. E.g. CH?CH?CH?

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5
Q

What is a displayed formula?

A

A formula showing the arrangement of atoms in a substance and all the bonds E.g.

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6
Q

What is a skeletal formula?

A

A simplified version of a displayed formula where straight lines represent carbon-carbon bonds e.g.

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7
Q

What is a hydrocarbon?

A

A compound made of atoms of hydrogen and carbon only

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8
Q

What is an alkane?

A

A hydrocarbon with only single bonds.

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9
Q

What is isomerism?

A

When molecules have the same atoms but they are arranged differently

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10
Q

What are the two main types of isomerism?

A

Structural isomerism and stereoisomerism

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11
Q

What is structural isomerism?

A

Where isomers have the same molecular formula but a different structure

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12
Q

What is chain isomerism?

A

Compounds that have the same molecular formula but the longest carbon chain differs

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13
Q

What is position isomerism?

A

Compounds that have the same molecular formula but the functional group is attached to the chain in a different position

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14
Q

What is functional group isomerism?

A

Compounds that have the same molecular formula but there are different functional groups

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15
Q

What is stereoisomerism?

A

Where isomers have the same structural formula but are arranged differently in 3D space

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16
Q

What are the two types of stereoisomerism?

A

E/Z isomerism and optical isomerism

17
Q

Why can E/Z isomers exist?

A

The C=C double bond can’t rotate

18
Q

What conditions does a molecule need to fulfil to exhibit E/Z isomerism?

A

C=C double bond and each carbon atom needs to have two different groups attached

19
Q

What is a chiral carbon?

A

Carbon atom with four different groups surrounding it

20
Q

What conditions does a molecule need to fulfil to exhibit optical isomerism?

A

Contain a chiral carbon

21
Q

What are enantiomers?

A

Molecules with the same structural formula but exhibiting optical isomerism

22
Q

What is the effect of two enantiomers on plane polarized light?

A

They rotate it in opposite directions

23
Q

What is a racemic mixture?

A

A 50:50 mixture of two enantiomers

24
Q

Explain the effect of a racemic mixture on plane polarized light

A

One enantiomer rotates the light clockwise and the other anti-clockwise, resulting in no net rotation.

25
Q

In a mechanism, what do curly arrows show?

A

The movement of electrons

26
Q

In a mechanism, where do curly arrows go from/to?

A

From electron sources (bond or lone pair) to electron sinks (atom/molecule/ion that can accept a new bond/lone pair)

27
Q

What is a nucleophile?

A

Electron rich species that contain an electron pair available for bonding

28
Q

Give examples of common nucleophiles

A

Ammonia, hydroxide ions, cyanide ions, water, alcohols, amines

29
Q

What is an electrophile?

A

Electron poor species that seek an electron pair available for bonding

30
Q

Give examples of common electrophiles

A

Hydrogen halides, halogen molecules, H2SO4, nitronium ion, acylium ions

31
Q

What is an addition mechanism?

A

Where the number of groups around the carbon atom increases

32
Q

What is a substitution mechanism?

A

Where the number of groups around the carbon atom stays the same, occuring in one step

33
Q

What is an elimination mechanism?

A

Where the number of groups around the carbon atom decreases

34
Q

What is an addition-elimination mechanism?

A

Where the number of groups around the carbon atom stays the same, occuring in two steps

35
Q

What compounds undergo electrophilic addition?

A

Alkenes

36
Q

What compounds undergo nucleophilic substitution?

A

Haloalkanes

37
Q

What compounds undergo elimination?

A

Haloalkanes, alcohols

38
Q

What compounds undergo nucleophilic addition-elimination reactions?

A

Acyl chlorides, aldehydes, ketones, acid anhydrides

39
Q

What compounds undergo electrophilic substitution?

A

Aromatic compounds

A Level chemistry Y12 (8 decks)

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