Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

AH Chemistry (short) > Unit 3- Organic chemistry and instrumental analysis > Flashcards

Unit 3- Organic chemistry and instrumental analysis Flashcards

You may prefer our related Brainscape-certified flashcards:
Periodic Table flashcards Chemistry 101 flashcards AP® Chemistry flashcards Organic Chemistry 101 flashcards
1
Q

When do molecular orbitals form?

A

When atomic orbitals combine

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is the number of molecular orbitals formed equal to?

A

The number of atomic orbitals that combine (2 atomic orbitals combine to make 2 molecular orbitals)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What does the combination of two atomic orbitals result in?

A

The formation of a bonding molecular orbital and an antibonding orbital

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Which of the two molecular orbitals (bonding and antibonding) encompasses both nuclei?

A

The bonding molecular orbital

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

In molecular orbital theory what is the basis of bonding between atoms?

A

The attraction of the positively charged nuclei and the negatively charged electrons

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

How many electrons can each molecular orbital hold?

A

Each molecular orbital can hold a maximum of 2 electrons

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What are sigma bonds?

A

Molecular orbitals that form by end-on overlap of atomic orbitals along the axis of the covalent bond

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What are pi bonds?

A

Molecular orbitals that form by side-on overlap of parallel atomic orbitals that lie perpendicular to the axis of the covalent bond

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is hybridisation?

A

The process of mixing atomic orbitals within an atom to generate a set of new atomic orbitals called hybrid orbitals

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What can be said about the new hybrid orbitals that are formed through hybridisation?

A

They are degenerate

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What kind of hybridisation takes place in alkanes?

A

The 2s orbital and the three 2p orbitals of carbon hybridise to form four degenerate sp^3 hybrid orbitals

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What arrangement do the sp^3 hybrid orbitals in alkanes adopt?

A

A tetrahedral arrangement

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What kind of hybridisation takes place in alkenes?

A

The 2s orbital and two of the 2p orbitals of carbon hybridise to form three degenerate sp^2 orbitals

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What can the bonding in benzene and other aromatic systems be described in terms of?

A

sp^2 hybridisation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Out of pure covalent molecules, polar covalent molecules and ionic molecules which show the most and least symmetry?

A 
Most= pure covalent 
Middle= polar covalent
Least= ionic covalent
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

In a triple bond how many sigma and pi bonds are there?

A

1 sigma bond and 2 pi bonds

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

The electronic configuration of an isolated carbon atom cannot explain the number of bonds formed by carbon atoms in molecules. What can be used to explain the bonding and shape of molecules of carbon?

A

Hybridisation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

In a double bond how many sigma and pi bonds are there?

A

1 sigma and 1 pi

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What kind of bond is present in a single bond?

A

A sigma bond

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What arrangement does sp^2 hybridisation in alkenes adopt?

A

A trigonal planar arrangement

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What can the binding in benzene and other aromatic molecules be described in terms of ?

A

Sp^2 hybridisation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What can be said about the electrons in benzene?

A

They are delocalised

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What arrangement do the sp hybrid orbitals in alkynes adopt?

A

A linear arrangement

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What is the HOMO?

A

The highest occupied molecular orbital, this is the highest bonding molecular orbital containing electrons

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

What is the LUMO?

A

The lowest unoccupied molecular orbital, this is the lowest anti-bonding molecular orbital

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

What can the absorption of electromagnetic energy in organic molecules cause to happen?

A

Electrons can be promoted from HOMO to LUMO

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

Why are most organic molecules colourless?

A

Because the energy difference between the HOMO and the LUMO is relatively large. This results in either electrons not making the jump or light being absorbed from the UV region of the electromagnetic spectrum

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

What is a chromosphere?

A

A group of atoms within a molecule that is responsible for the absorption of light in the visible region of the spectrum

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

What does it mean if their are more atoms in a conjugated system?

A

The more atoms there are the lower the energy gap between the HOMO and the LUMO. This means a higher wavelength of light will be absorbed

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

What is the process of bond breaking also known as?

A

Bond fission

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

What are the two types of bond fission?

A

Homolytic and heterolytic

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

What does homolytic fission result in?

A

The formation of 2 neutral radicals

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

What does heterolytic fission result in?

A

The formation of 2 oppositely charged ions

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
34
Q

Which of homolytic and heterolytic fission is more suitable for organic synthesis and why?

A

Heterolytic fission, as they tend to result in fewer and less complex products

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
35
Q

In reactions involving bond fission, what are attacking groups classified as?

A

Either nucleophiles or electrophiles

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
36
Q

What are nucleophiles?

A
  • negatively charged ions or neutral molecules
  • electron rich
  • attracted towards atoms bearing a partial or full positive charge
  • capable of donating an electron pair to form a new covalent bond
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
37
Q

What are electrophiles?

A
  • positively charged ions or neutral molecules
  • electron deficient
  • attracted towards atoms bearing a partial or full negative charge
  • capable of accepting an electron pair to form a new covalent bond
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
38
Q

What 2 types of reaction are most commonly associated with alkenes (double bonds)?

A

Addition and elimination

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
39
Q

What is the difference between aldehydes and ketones?

A

Aldehydes have a double bonded oxygen at the end of the carbon chain whereas in ketones it is in the middle of the chain

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
40
Q

What is hydration?

A

An addition reaction (breaking a double bond) involving water

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
41
Q

What is a condensation reaction?

A

Two molecules combine to form another, usually with the loss of a small molecule like water

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
42
Q

What is the opposite reaction if condensation?

A

Hydrolysis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
43
Q

What happens in a neutralisation reaction?

A

An acid and a base are combined to form a neutral substance

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
44
Q

How can aldehydes be prepared?

A

From the oxidation of primary alcohols

45
Q

Can aldehydes and ketones be further oxidised?

A

Ketones cannot but aldehydes can be further oxidised to form carboxylic acids

46
Q

How can ketones be prepared?

A

From the oxidation of secondary alcohols

47
Q

What is the opposite of an addition reaction?

A

An elimination reaction

48
Q

When naming esters where do the two parts of the name come from?

A

The first part comes from the alcohol and the second part comes from the carboxylic acid

49
Q

What are the two ways to synthesis a haloalkane?

A
  1. Addition reaction of an alkene and a hydrogen halide to form a monohaloalkane
  2. Addition reaction of an alkene and a halogen to form a dihaloalkane
50
Q

What are the 3 nucleophilic substitution reactions a haloalkane can undergo?

A
  1. Haloalkane reacts with aqueous NaOH or KOH to form an alcohol
  2. Haloalkane reacts with ethanolic cyanide to form a nitrile
  3. Haloalkane reacts with an alcoholic alkoxide to form an ether
51
Q

What can happen to nitriles after they are synthesised from a haloalkane?

A

They can be hydrolysed to form a carboxylic acid

52
Q

What happens during the reaction between a haloalkane and ethanolic cyanide to form a nitrile?

A

The carbon chain length is increased by 1

53
Q

How do you form an alcoholic alkoxide?

A

By reaction an alkaline metal with an alcohol

54
Q

What can be said about the Sn1 mechanism for haloalkanes?

A
  • takes a minimum of 2 steps
  • only 1 species in the rate determining step
  • occurs via a trigonal planar carbocation intermediate
  • a racemix mixture is formed
  • used for tertiary haloalkanes
55
Q

What can be said about the Sn2 mechanism for haloalkanes?

A
  • takes 1 step
  • 2 species in the rate determining step
  • used for primary and sometimes secondary haloalkanes
56
Q

Why is a race mix mixture formed during the Sn1 haloalkane mechanism?

A

Because the nucleophile can attack from either side

57
Q

What is the 1 elimination reaction that haloalkanes can undergo?

A
  • haloalkane reacts with a strong base (NaOH or KOH) in ethanol to form an alkene
58
Q

When does hydrogen bonding occur?

A

When hydrogen is covalently bonded to either fluorine, oxygen or nitrogen

59
Q

What are 4 properties of alcohols?

A
  • high melting and boiling points due to OH group
  • high solubility (however longer chain alcohols are not soluble)
  • highly flammable
  • good solvents
60
Q

What are the 3 ways to prepare alcohols?

A
  1. Nucleophilic substitution of a haloalkane with aqueous NaOH or KOH
  2. Reduction of either a aldehyde, ketone or carboxylic acid using LiAlH4
  3. Acid-catalysed hydration of an alkene
61
Q

What are the 4 reactions an alcohol can undertake?

A
  1. Oxidation of primary alcohols to form aldehydes and then carboxylic acids or secondary alcohols to form ketones
  2. Dehydration of alcohols to form alkenes using either Al2O3, H2SO4 or H3PO4
  3. Condensation reaction to form an ester either using a carboxylic acid or a acid chloride
  4. Reaction between an alcohol and a reactive metal to form an alcoholic alkoxide which can then react with a monohaloalkane to form an ether
62
Q

What are the 2 methods of forming an ester and which is the preferred method?

A
  1. Condensation reaction of an alcohol with a carboxylic acid using conc. H2SO4 as a catalyst
  2. Condensation reaction of an alcohol with a acid chloride

Method 2 with the acid chloride is preferred as it is faster, not reversible and does not require a catalyst

63
Q

What are 3 properties of ethers?

A
  • low boiling points
  • good solvents
  • small ethers are soluble in water, large ethers are not
64
Q

What are the 2 ways in which a alkene can be prepared?

A
  1. The dehydration of alcohols using either Al2O3, conc. H2SO4 or conc. H3PO4 as a catalyst
  2. The base-induced elimination of hydrogen halides from monohaloalkanes
65
Q

What are the 4 electrophiles addition reactions an alkene can undergo?

A
  1. The hyd
66
Q

What are the 4 electrophiles addition reactions an alkene can undergo?

A
  1. Hydrogenation (adding H+) to produce alkanes using a catalyst
  2. Addition reaction of an alkene and a halogen to produce a dihaloalkane
  3. Addition reaction of a alkene and a hydrogen halos to form a monohaloalkane
  4. Acid-catalysed hydration (addition water) to form an alcohol
67
Q

What are the 5 ways in which a carboxylic acid can be prepared?

A
  1. Oxidising a primary alcohol using a oxidising agent
  2. Oxidising a aldehyde using an oxidising agent
  3. Acid or alkali hydrolysis of esters
  4. Acid or alkali hydrolysis of amides
  5. Acid hydrolysis of nitriles
68
Q

What are the 4 reactions a carboxylic acid can undergo?

A
  1. Neutralisation reaction with a base to produce a salt
  2. Condensation reaction with an alcohol to form an ester, using either conc. H2SO4 or conc. H3PO4 as a catalyst
  3. Reaction with an amine to form an amide using heat
  4. Reduction reaction to form primary alcohols using LiAlH4
69
Q

What do primary and secondary amines have that tertiary ones don’t?

A

Hydrogen bonding (N-H)

70
Q

What can be said about boiling points of amines?

A

Primary and secondary amines have higher boiling points than comparative tertiary amines due to their hydrogen bonding

71
Q

What can be said about the solubility of amines?

A

All types of amines can hydrogen bond with water which makes them soluble, smaller chain amines are more soluble

72
Q

What is the molecular formula of benzene?

A

C6H6

73
Q

What is the stability of the benzene ring due to?

A

The delocalisation of electrons in the conjugated system

74
Q

What is a phenyl group?

A

A benzene ring in which 1 hydrogen has been substituted by another group. It has the formula C6H5-

75
Q

What kind of reaction can benzene take part in?

A

Electrophilic substitution

76
Q

What are the 4 reactions benzene can undergo?

A
  1. Halogenation by reaction with a halogen using a catalyst
  2. Alkylation by reaction with a haloalkane using aluminium chloride as a catalyst
  3. Nitration by reaction with conc. sulphuric acid and conc. nitric acid
  4. Sulfonation by reaction with conc. sulphuric acid
77
Q

What are isomers?

A

Molecules with the same molecular formula but different structural formulae

78
Q

What is the difference between structural isomers and stereoisomers?

A

Structural isomers occur when atoms are bonded together in a different order in each isomer. Stereoisomers occur when the order of the bonding in the atoms is the same but the spatial arrangement of the atoms is different in each isomer

79
Q

What are the 2 types of stereoisomers?

A

Geometric and optical

80
Q

What can be said about melting and boiling points in cis and trans isomers?

A

Trans isomers will have higher melting and boiling points as the molecules are packed tighter together allowing more intermolecular forces to be formed

81
Q

When do optical isomers occur?

A

In compounds in which four different groups are arranged tetrahedrally around a central carbon atom

82
Q

What can the carbon atom in the centre of a optical isomer be referred to as?

A

The chiral carbon or the chiral centre

83
Q

What are enantiomers?

A

A pair of isomers that are non-superimposable mirror images of each other

84
Q

Optical isomers have identical physical properties apart from…?

A

Their effect on plane-polarised light

85
Q

Optical isomers have identical chemical properties apart from…?

A

When in a chiral environment such as that found in biological systems

86
Q

What do optical isomers do to plane-polarised light?

A

Rotate it by the same amount but in different directions and so are optically active

87
Q

What is formed if both enantiomers are present in equal amounts?

A

A racemix mixture, this will be optically inactive as the rotational effect of the plane-polarised light will cancel out

88
Q

What are drugs?

A

Substances that alter the biochemical processes in the body

89
Q

What are medicines?

A

Drugs that have beneficial effects

90
Q

What is usually added to a medicine other than the drug?

A

Fillers to add bulk or sweeteners to improve the taste

91
Q

How do drugs generally work?

A

By binding to specific protein molecules, these can either be found on the cell surface (receptor) or can be enzyme specific molecules within the cell

92
Q

What does an agonist do?

A

Mimics the natural compound and generates a similar response

93
Q

What does an antagonist do?

A

Prevents the natural compound from binding and blocks the natural response from occurring

94
Q

What can many drugs that act on enzymes be classified as?

A

Enzyme inhibitors

95
Q

How do enzyme inhibitors work?

A

By binding to the active site of the enzyme and blocking the reaction normally catalysed there

96
Q

What are the types of interactions that can form between a drug and a receptor binding site?

A

van der Waals forces and/or ionic bonds

97
Q

What does the structural fragment of a drug molecule that allows it to form interactions with a receptor binding site or to an enzyme normally consists of?

A

Different functional groups correctly orientated with respect to each other

98
Q

What is elemental microanalysis used to determine?

A

The masses of C, H, O, S and N in a sample of an organic compound

99
Q

What does an empirical formula show?

A

The simplest ratio of the elements in a molecule

100
Q

What can mass spectrometry be used to determine?

A

A accurate gram formula mass (gfm) and structural features of an organic compound

101
Q

What happens in mass spectrometry?

A
  • a small sample of an organic compound is bombarded by high energy electrons
  • this removes electrons from the organic molecule generating positively charged molecular ions called parent ions
  • these molecular ions then break into smaller positively charged ion fragments
  • a mass spectrum is obtained showing a plot of the relative abundance of the ions detected against the mass-to-charge ratio
102
Q

What is infrared spectroscopy used for?

A

Identifying certain functional groups in an organic compound

103
Q

What happens in infrared spectroscopy?

A

Infrared radiation is absorbed by organic compounds, bonds within the molecule vibrate (stretch and bend). The wavelengths that are absorbed depend on the type of atoms that make up the bond and the strength of the bond

104
Q

How does infrared spectroscopy work?

A

Infrared radiation is passed through a sample of the organic compound and then into a detector that measures the intensity of the transmitted radiation at different wavelengths. The absorbable of infrared radiation is measured in wavenumbers

105
Q

What is wavenumber?

A

The reciprocal of wavelength, 1/wavelength. It is given in units cm-1

106
Q

What can proton NMR spectroscopy give information on?

A

The different chemical environments of hydrogen atoms in an organic molecule, and how many hydrogen atoms are in each of these environments

107
Q

How does proton NMR spectroscopy work?

A

H nuclei behave like tiny magnets in a strong magnetic field. Some align with the field (lower energy), whilst the rest align against it. Absorption of radiation in the in the radio frequency region of the EM spectrum causes the H nuclei to flip from the lower to higher energy alignment. As they fall back to the lower energy alignment the emitted radiation is detected and plotted in the spectrum.

108
Q

What is the standard reference used in proton NMR?

A

Tetramethylsilane (TMS), it is assigned a chemical shift value equal to zero

109
Q

What is the difference between high and low resolution proton NMR?

A

High-resolution proton NMR uses higher radio frequencies than those used in low-resolution proton NMR and also provides a more detailed spectra

AH Chemistry (short) (4 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions