Topic 2 and 12
Describe how the relative atomic mass of a sample of calcium could be determined from its
mass spectrum
- Multiply relative intensity by m/z value of each isotope; find the weighted average
Outline the source of colours and why they are different for different elements
- Promoted electrons are relaxed to lower energy levels; different because the
difference between energy levels is different for different elements
Topic 3 and 13
Outline what would happen to the wavelengths at which the vanadium complex ions would
absorb light as the water molecules are gradually replaced with chloride ions
- Cl- is a weaker ligand; absorption wavelength increases
Outline why there is an increase in ionization energy
- As more electrons are removed, the pull of the nucleus / positive ions holds the
remaining electrons more tightly
Explain the large increase in ionization energy for V
- 5th electron is lost from the valence shell
- 6th electron is lost from a complete inner shell
- The inner shell is less well shielded / closer to the nucleus
Describe the trend in acid-base properties of the oxides of period 3
- Basic to acidic; through amphoteric
Explain the decrease in atomic radius from Na to Cl
- Nuclear charge increases to electrons are pulled more closely to the nucleus
- Elements in the same energy level so similar shielding
Explain why Na+ has a smaller ionic radius that O2-
- Same electron configuration; Na+ has more protons
Outline why chlorine has a smaller atomic radius than sulfur
- Occupy the same number of energy levels / have similar shielding; chlorine has one
more proton causing a stronger pull on the electrons
Explain why a copper (II) solution is blue
- Orange light is absorbed «and the complementary colour is observed»
- Any TWO from: partially filled d-orbitals / «ligands/water cause» d-orbitals «to» split
/ light is absorbed as electrons move to a higher energy orbital «in d–d transitions»
OR light is absorbed as electrons are promoted / energy gap corresponds to «orange»
light in the visible region of the spectrum
Topic 4 and 14
State what is meant by resonance
- More than one possible position for a pi bond
Describe the nature of ionic bonding
- Lattice; electrostatic attractions between oppositely charged ions
Suggest why a three-membered ring is unstable
- The bond angle is 60 / strained
Describe the bonding in metals
, - Electrostatic attractions; lattice of positively charges ions AND sea of delocalized
electrons
Topic 5 and 15
Predict whether Mn2+ or Fe2+ s more likely to have a more exothermin enthalpy of
hydration
- Fe2+ because it has a smaller ionic radius; stronger interaction with water molecules
Topic 6 and 16
Explain how you attempt to confirm this rate expression, giving the results you would expect
- Test the effect on reaction rate by varying the concentrations of each reactant
independently; doubling [X] doubles rate, etc
Explain why a higher temperature causes the rate of reaction to increase
- Greater proportion of molecules have E ≥ Ea or E > Ea OR greater area under curve
to the right of the Ea; greater frequency of collisions «between molecules» OR more
collisions per unit time/second
Topic 8 and 18
Suggest why oxides of phosphorous are not major contributors to acid deposition
- Phosphorous is not commonly found in the air / low levels of phosphorous in the air
Outline one technique of pre and post-combustion methods to minimize sulphur dioxide
- Pre-combustion: remove sulphur-containing compounds
- Post-combustion: remove it by neutralization / reaction with alkaline
Suggest why it is more convenient to expressacidity using the pH scale rather than the
concentration of hydrogen ions
- Reduces a wide range of numbers to a small range OR simple/easy to use OR
converts exponential expressions into a linear scale/simple numbers
Topic 9 and 19
Oxidation is now defined in terms of change in oxidation number. Explore how earlier
definitions of oxidation and reduction may have led to conflicting answers.
- Oxygen gained so it could be oxidation; hydrogen also gained so it could be
reduction; oxidation increases so it must be oxidation
Topic 10 and 20
Phenylamine is produced by the reduction of nitrobenzene. Suggest how this conversion
could be carried out
- Heat with tin and HCl; aqueous alkali / OH-
When one enantiomer undergoes substitution by alkaline hydrolysis, approximately 75% of
the product molecules show inversion of configuration. Comment on the mechanisms that
occur
- Sn1 would give approximately 50% of each; so mechanism is a mixture of both Sn1
and Sn2
Describe how the relative atomic mass of a sample of calcium could be determined from its
mass spectrum
- Multiply relative intensity by m/z value of each isotope; find the weighted average
Outline the source of colours and why they are different for different elements
- Promoted electrons are relaxed to lower energy levels; different because the
difference between energy levels is different for different elements
Topic 3 and 13
Outline what would happen to the wavelengths at which the vanadium complex ions would
absorb light as the water molecules are gradually replaced with chloride ions
- Cl- is a weaker ligand; absorption wavelength increases
Outline why there is an increase in ionization energy
- As more electrons are removed, the pull of the nucleus / positive ions holds the
remaining electrons more tightly
Explain the large increase in ionization energy for V
- 5th electron is lost from the valence shell
- 6th electron is lost from a complete inner shell
- The inner shell is less well shielded / closer to the nucleus
Describe the trend in acid-base properties of the oxides of period 3
- Basic to acidic; through amphoteric
Explain the decrease in atomic radius from Na to Cl
- Nuclear charge increases to electrons are pulled more closely to the nucleus
- Elements in the same energy level so similar shielding
Explain why Na+ has a smaller ionic radius that O2-
- Same electron configuration; Na+ has more protons
Outline why chlorine has a smaller atomic radius than sulfur
- Occupy the same number of energy levels / have similar shielding; chlorine has one
more proton causing a stronger pull on the electrons
Explain why a copper (II) solution is blue
- Orange light is absorbed «and the complementary colour is observed»
- Any TWO from: partially filled d-orbitals / «ligands/water cause» d-orbitals «to» split
/ light is absorbed as electrons move to a higher energy orbital «in d–d transitions»
OR light is absorbed as electrons are promoted / energy gap corresponds to «orange»
light in the visible region of the spectrum
Topic 4 and 14
State what is meant by resonance
- More than one possible position for a pi bond
Describe the nature of ionic bonding
- Lattice; electrostatic attractions between oppositely charged ions
Suggest why a three-membered ring is unstable
- The bond angle is 60 / strained
Describe the bonding in metals
, - Electrostatic attractions; lattice of positively charges ions AND sea of delocalized
electrons
Topic 5 and 15
Predict whether Mn2+ or Fe2+ s more likely to have a more exothermin enthalpy of
hydration
- Fe2+ because it has a smaller ionic radius; stronger interaction with water molecules
Topic 6 and 16
Explain how you attempt to confirm this rate expression, giving the results you would expect
- Test the effect on reaction rate by varying the concentrations of each reactant
independently; doubling [X] doubles rate, etc
Explain why a higher temperature causes the rate of reaction to increase
- Greater proportion of molecules have E ≥ Ea or E > Ea OR greater area under curve
to the right of the Ea; greater frequency of collisions «between molecules» OR more
collisions per unit time/second
Topic 8 and 18
Suggest why oxides of phosphorous are not major contributors to acid deposition
- Phosphorous is not commonly found in the air / low levels of phosphorous in the air
Outline one technique of pre and post-combustion methods to minimize sulphur dioxide
- Pre-combustion: remove sulphur-containing compounds
- Post-combustion: remove it by neutralization / reaction with alkaline
Suggest why it is more convenient to expressacidity using the pH scale rather than the
concentration of hydrogen ions
- Reduces a wide range of numbers to a small range OR simple/easy to use OR
converts exponential expressions into a linear scale/simple numbers
Topic 9 and 19
Oxidation is now defined in terms of change in oxidation number. Explore how earlier
definitions of oxidation and reduction may have led to conflicting answers.
- Oxygen gained so it could be oxidation; hydrogen also gained so it could be
reduction; oxidation increases so it must be oxidation
Topic 10 and 20
Phenylamine is produced by the reduction of nitrobenzene. Suggest how this conversion
could be carried out
- Heat with tin and HCl; aqueous alkali / OH-
When one enantiomer undergoes substitution by alkaline hydrolysis, approximately 75% of
the product molecules show inversion of configuration. Comment on the mechanisms that
occur
- Sn1 would give approximately 50% of each; so mechanism is a mixture of both Sn1
and Sn2
