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Chemisty A Level OCR > Organic Chemistry > Flashcards

Organic Chemistry Flashcards

1
Q

Definition of structural isomers

A

They have the same molecular formula but different structural formulae.

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2
Q

What’s the difference in boiling points between isomers?

A

Straight chained isomers have higher boiling points than branched chained isomers.
The more branching the lower the boiling point.

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3
Q

Why do branched chains have lower boiling points than straight chains?

A

Branched chains decrease the effectiveness of intermolecular attractive forces so less energy is needed to separate the molecules. The functional group makes it lower/higher.

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4
Q

What is E/Z isomerism?

A

A form of stereoisomerism.

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5
Q

Where are E/Z isomerisms found?

A

They are found in alkenes due to the restricted rotation of C=C bonds because the pi bonds are denser above and below the sigma bonds.

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6
Q

What are the two types of of E/Z isomerism?

A

Z:Zusammen/Cis: higher priority groups are on the same side of C=C.
E:Entgegen/Trans: higher priority groups are on the opposite sides of C=C.

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7
Q

If the similar atoms are on the same end of the C=C is it a Cis/Trans isomer?

A

No

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8
Q

What is mass spectrometry?

A

Ionisation- atom is ionised to give it a positive charge.
Acceleration- gives them all the same kinetic energy.
Deflection- the ions are deflected by a magnetic field according to their mass. The lighter they are the more they deflect.
Detection-the beam of ions passing through the machine is detected electrically.

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9
Q

How does infrared spectroscopy work?

A

It works on the absorption of bonds over a wide range of wave numbers.

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10
Q

What do the position of the peaks depend on?

A

Bond strength

Mass of the atoms joined by the bond

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11
Q

Strong bonds and light atoms….

A

Absorb at lower wavenumbers because they vibrate faster.

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12
Q

Uses of infrared spectroscopy in real life

A

Used to identify pollutants by their IR spectral fingerprints, it is used in cars to measure carbon monoxide levels.

Used in breathalysers to find the compounds in the breath.

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13
Q

How does infrared radiation effect atmospheric gases?

A

IR radiation is relatively unaffected by atmospheric gases. The radiation passes through the atmosphere and is absorbed or re emitted to the earths surface I the form of Ali get wave length. Greenhouse gasses absorb the longer wavelength IR radiation this increases the temperature of the earth.

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14
Q

What is a haloalkane?

A

Halogen is attached to an aliphatic skeleton- alkyl group.

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15
Q

What is the trend in boiling points for haloalkanes?

A

The boiling point increases with mass. For isometric compounds the greater the branching the lower the boiling point.

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16
Q

How soluble are haloalkanes?

A

Haloalkanes are soluble in organic solvents but insoluble in water- they aren’t polar enough and don’t exhibit hydrogen bonding.

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17
Q

Do halogens have a greater electronegativity than carbon?

A

Yes

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18
Q

Name an example of a nucleophile

A

OH-
CN-
NH3
H2O

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19
Q

What does aliphatic mean?

A

Carbon atoms are joined to each other in unbraced (straight) or branched chains, or non- aromatic chains.

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20
Q

What does alicyclics mean?

A

Carbon atoms are joined each other in a ring, with or without branches.

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21
Q

What does aromatic mean?

A

Some or all of the carbon atoms are found in a benzene ring.

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22
Q

Definition of Alkane

A

Contains single carbon-to-carbon atoms.

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23
Q

Definition of alkene

A

Contains at least one double carbon-to-carbon bond

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24
Q

Definition of alkyne

A

Contains at least one triple carbon-to-carbon bond.

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25
Q

What is the molecular formula?

A

This shows the number of atoms of each element present in a molecule.

26
Q

What is the definition of empirical formula?

A

The empirical formula is the simplest whole number ratio of the atoms of each element present in a compound.

27
Q

What is the definition of general formula?

A

The simplest algebraic formula for any member of a homologous series.

28
Q

What is the definition of displayed formula?

A

A displayed formula shows the relative positioning of all the atoms in a molecule and the bonds between them.

29
Q

What is the definition of structural formula?

A

The structural formula uses the smallest amount of detail necessary to show the arrangement the atoms in a molecule.

30
Q

What are structural isomers?

A

These are compounds with the same molecular formula but different structural formulae.

31
Q

What occurs when isomers have the same functional group?

A

The functional group can be a t different positions along the carbon chain.

32
Q

What occurs when isomers have different functional groups?

A

Sometimes who molecules containing different functional groups have the same molecular formula so can be presented in different ways.

33
Q

What are the two types of bond fission?

A

Homolytic fission

Heterolytic fission

34
Q

What is homolytic fission?

A

When a covalent bond breaks by homolytic fission, each of the bonded atoms takes one of the shared pair of electrons from the bond. Each atom now has a single unpaired electron.

35
Q

What is a radical?

A

An atom or group of atoms with an unpaired electron.

36
Q

What is heterolytic fission?

A

When a covalent bond by heterolytic fission, one of the bonded atoms takes both of the electrons from the bond.

The atom that takes both becomes a negative ion.
The atoms that doesn’t take the electrons become a positive ion.
H3c-cl –> H3c+ + cl-

37
Q

What are curly arrows?

A

They show the movement of electron pairs when bonds are being broken or made.

38
Q

How are curly arrows shown in homolytic fission?

A

Fish-hook arrows

39
Q

What are the 3 types of reactions?

A

Addition
Substitution
Elimination

40
Q

What is an addition reaction?

A

Two reactants join together to form one product.

41
Q

What is a substitution reaction?

A

An atom or group of atoms is replaced by a different atom or group of atoms.

42
Q

What is an elimination reaction?

A

Involves the removal of a small molecule from a larger one. In an elimination reaction, one reactant molecule forms two products.

43
Q

What is the bonding like in alkanes?

A

Joined together by single covalent bonds

4 sigma bonds and 1 pi bond.

44
Q

What is the shape of alkanes like?

A

Each bond angle has 109.5 degrees and has a 3D tetrahedral shape.

45
Q

What is the trend in boiling point and why?

A

Increases
Weak intermolecular forces called London forces. They hold molecules together in solids, but when a liquid molecules move apart from each other and the alkane become a gas.
More intermolecular forces, the higher the boiling point.

46
Q

What is the effect of chain length on boiling points in alkanes?

A

As the chain length increase, the molecules have a larger surface area, so more surface contact is possible between molecules. The London forces will be greater so more energy is needed to overcome these forces.

47
Q

What is the effect of branching on boiling points of alkanes?

A

Decreases
The shape prevents branched chains being close to each other decreasing intermolecular forces.
Less surface points so fewer London forces.

48
Q

What are unsaturated hydrocarbons?

A

Alkenes- they have a double bond which makes them unsaturated.

49
Q

How many sigma bonds are they in each carbon in a double bond?

A

3

50
Q

How is a pi bond formed?

A

A pi bond is formed by the sideways overlap of 2 p orbitals, one from each carbon atom of the double bond.

51
Q

What is the bond angle of an alkene?

A

120 degrees

52
Q

What are the conditions needs for the hydrogenation of alkenes?

A

Nickel catalyst

423K

53
Q

What is hydrogenation?

A

An addition reaction, in which hydrogen is added across a double bond.
All C=C bonds react with hydrogen this way.

54
Q

Is the halogenation of alkenes an addition reaction?

A

Yes

Alkenes undergo a rapid addition reaction with the halogens chlorine or bro,Ines at room temperature.

55
Q

How do you test for unsaturation?

A 
Bromine water (an orange solution) is added to a sample of alkene, bromine adds across the double bond. 
The orange colour disappears if the solution is an alkene.
56
Q

What conditions are needed for addition reactions of alkenes with hydrogen halides?

A

Room temperature

57
Q

What is formed when alkenes are hydrated?

A

Alcohols are formed

58
Q

What conditions are needed for hydration reactions of alkenes?

A

Steam

Phosphoric acid catalyst

59
Q

What is the alcohol homologous series?

A

Hydroxyl group

60
Q

What are the three groups alcohols can be classified in to?

A

Primary
Secondary
Tertiary

61
Q

What is a primary alcohols?

A

The -OH group I attached to a carbon atom that is attached to a carbon atom that is attached to two hydrogen atoms and one alkyl groups

Chemisty A Level OCR (5 decks)

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