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WJEC A-Level Chemistry > 2.4 - Organic Compounds > Flashcards

2.4 - Organic Compounds Flashcards

1
Q

What is a homologous series?

A

A series of organic compounds with the same functional group and where each successive member differs by CH2. The compounds have the same general formula.

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2
Q

What is a functional group?

A

An atom or group of atoms responsible for the characteristic reactions of that compound.

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3
Q

What is a structural formula?

A

A structural formula shows the number, type and arrangement of atoms in the molecule.
- Butane: CH3CH2CH2CH3
- Propan-2-ol: CH(3)CH(OH)CH(3)

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4
Q

What is a displayed formula?

A
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5
Q

What is a skeletal formula?

A
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6
Q

What is the general formula of alkanes?

A

C(n)H(2n+2)

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7
Q

Give the name and molecular formula of the first four alkanes

A

Methane - CH4
Ethane - C2H6
Propane - C3H8
Butane - C4H10

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8
Q

What is the functional group and general formula of alkenes?

A

Functional group: C=C
General formula: C(n)H(2n)

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9
Q

Give the name and molecular formula of the first four alkenes

A

Ethene - C(2)H(4)
Propene - C(3)H(6)
Butene - C(4)H(8)
Pentene - C(5)H(10)

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10
Q

What are halogenoalkanes?

A

Halogenoalkanes are compounds in which at least one hydrogen atom of an alkane has been replaced by a halogen atom.

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11
Q

How are halogenoalkanes named?

A
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12
Q
A
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13
Q

What is an alcohol?

A
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14
Q

What is the difference between primary, secondary and tertiary alcohols?

A
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15
Q

How are alcohols named?

A

Alcohols generally have the suffix -ol.
E.g. Ethanol, Propan-2-ol, butan-1,3-diol
They sometimes have the prefix hydroxy- if the suffix of the compound is taken by a different functional group.

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16
Q
A
17
Q

What is a carboxylic acid?

A
18
Q

How are carboxylic acids named?

A

Carboxylic acids have the suffix -oic acid.
E.g. Ethanoic acid, Propanedioic acid

19
Q
A
20
Q

How does the chain length affect the melting/boiling point of an organic compound?

A

The longer the chain length, the higher the melting/boiling point.
This is because the longer the carbon chain, the more points of contact there are between molecules. This means there are stronger temporary dipoles between the molecules so more energy is required to overcome the intermolecular forces.

21
Q

How does the chain length affect the solubility of an alcohol?

A

As chain length increases, alcohols become less soluble in water. In water, the alcohol OH group forms a hydrogen bond with water which replaces hydrogen bonds between water molecules. Only the OH group in alcohols can form H bonds, so longer alcohols disrupt the hydrogen bonding between water molecules but don’t replace them with additional H bonds, as the CH2 groups do not form these.

22
Q

Why are alcohols and carboxylic acids soluble in water?

A

Carboxylic acids and alcohols can form hydrogen bonds with water molecules and therefore they are soluble in water.

23
Q

Compare the boiling points of alcohols, alkanes and carboxylic acids

A

Alkanes < alcohols < carboxylic acids
Alkanes have the lowest boiling points because they only have temporary dipole forces between molecules, which are relatively easily overcome.
Alcohols and carboxylic acids both form hydrogen bonds which require a lot of energy to overcome and therefore they have higher boiling points. Carboxylic acids have the highest boiling points because two possible hydrogen bonds can be formed per carboxylic acid molecule.

24
Q

What is structural isomerism?

A

Structural isomerism is when compounds have the same molecular formula but a different arrangement of atoms (different structural formula).

25
Q

What are the three types of structural isomerism?

A
  • Chain isomerism
  • Functional group isomerism
  • Position isomerism
26
Q
A
27
Q

What are the different structural isomers of C(5)H(12)?

A
28
Q

What is a nucleophile?

A

A nucleophile is a species that donates a lone pair of electrons in a reaction.

29
Q

What is an electrophile?

A

An electrophile is a species that accepts a lone pair of electrons in a reaction.

30
Q

What is heterolytic bond fission?

A

Heterolytic bond fission is the breaking of a covalent bond where one of the bonded atoms gets both electrons. This produces one nucleophile and one electrophile.

31
Q

What is homolytic bond fission?

A

Homolytic bond fission is the breaking of a covalent bond where both bonded atoms get one electron, producing free radicals.

32
Q

What is a free radical?

A

A free radical is a neutral molecule that has an unpaired electron.

WJEC A-Level Chemistry (35 decks)

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